ANNUAL REPORT OF THE

WATER DEVELOPMENT DEPARTMENT

FOR THE YEAR 1960

CONTENTS

Photographs

I Introduction

If Policy III Organiz

Introduction

Progress made in 1960 was in some ways disappointing. Though the State of Emergency which was declared in 1959 was removed in June, 1960, the state of unrest in the territory prevailed throughout the year and the Department's activities were hampered by lack of co-operation and, in some cases, by deliberate obstruction from the people. This was particularly unfortunate because 1960 was a year of poor rainfall and towards the end of the dry season much hardship was experienced in the villages due to water shortages which might have been relieved had the villagers been willing to co-operate with the Department.

The acute shortage of staff experienced in Ul!5D continued in 1960 due to difficulty in expatriate recruitment which was probably in part attributable to the reports of the disturbed state of the territory. In particular there was a shortage of \Vater Development Engineer and Hydrological Assistant staff.

As a result of the adverse conditions the Department's output of work has been below average; there has been little increase in the scope of the hydrological survey of Nyasaland, though no ground has been lost, and the year's production of III bored wells was rather low, mainly due to obstructionism in the Northern Province. Full details of these and other aspects of the Department's work are given in the body of this report which covers the activities of the Department for the calendar year 1960. It should be noted however that the hydrological data given in the appendices relate to the hydrological year which ended on 31st October, 1960.

n. Policy The policy of the Department remains unchanged: the aim is to ensure that the

hest use is made of the water resources of Nyasaland, to conserve and increase the water resources available for use by man, to develop the uses of water, and to arrange that harmful excesses of water do the least amount of damage.

The first phase in the implementation of the policy is hydrological surveying and this work forms a major part of the Department's activities. In general the rate of development of the hydrological survey of Nyasaland is held to he fairly adequate when considered in relation to the stage of development of the territory. The work is largely concerned with the collection of statistics and the most im.portant factor in improving the value of the survey is extending the length of the records in time.

The full implementation of the policy is at present beyond the power of the Department because of personnel, financial and legal limitations, and therefore the further phases in the implem.entation are not so adequately carried out as the first phase, although there is no ph,Lse on which some work is not done.

In respect of conservation of water resources the Department acts in two ways: it helps to prevent waste of water resources by advising the Governm.ent on the granting of water licences and it helps to conserve surface water by advising fanners on the construction of dams and weirs. This second service is chiefly undertaken in connection with dams and weirs built under the Farmers Loans and Subsidies Scheme. The need for further conservation measures is apparent but it cannot at present be satisfied.

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To date the Department has taken no direct action for the conservation and increasing of ground water resources except that in the Blantyre-Limbe Township area it was found necessary during the year to restrict the drilling of private bored wells and the Department was the adviser on whether or not licences to drill should be granted. Fortunately, however, the measures advocated by other Government Departments for soil conservation and fire control are also ground water conservation measures and form what is probably the best method for the overall improvement of the gronnd water resources. The Department is represented on the three Provincial Natural Resources Boards and on the Fire Education Committee which are all concerned with the encouragement and enforcement of conservation measures.

In developing the use of water the Department has two main lines of action, advisory and direct. As part of the advisory service, persons engaged in water engineering work in the territory may use the hydrological data collected by the Department and are advised on water engineering problems. vVhere the work is required for a Government agency the Department may supply detailed designs for the works.

Direct action is at present confined to the development of the ground water resources by bored wells. The Department drills and maintains bored wells for village water supplies and drills bored wells for township and station water supplies. The Department also administers the borehole subsidy part of the Farmers' Loans and Subsidies Scheme.

In arranging that excesses of water do no harm, the Departmen t operates a flood warning service in the Lower Shire area and advises on drainage problems. In particularit frequently gives advice on the flood flows to be anticipated at road culverts and bridges.

In view of the water shortages experienced in the last two years, considerable interest has been shown by the public in water development matters and during 1960 an effort was made to turn this interest to advantage in seeking more help from villagers in improving their village water supplies schemes. Due to the unfavourable political climate in the territory little new response was aroused, but this way of trying to increase the output of the Department will be pursued in the hope of better conditions in the future.

Ill. Organization

The organization of the Department has remained basically the same, though modifications have had to be made from time to time in order to suit the varying staff position. The well boring section and the Southern Province wells maintenance section has continued to be run by headquarters staff, but all other field work has been organized on a Divisional basis though, due to the shortage of engineer staff, for the most of the year all three Divisions lacked Divisional Engineers and were headed hy Hydrological Assistant staff.

Mr. R. G. Gale took up the appointment of Senior Executive Engineer on Ist February, and Mr. A. Buchanan relinquished the acting appointment to the post, remaining at headquarters as Development Engineer until he left on vacation leave pending termination of contract on 7th August.

On 27th July the Director proceeded on vacation leave and the Senior Executive Engineer was appointed as Acting Director. For lack of engineer staff of sufficient service no acting appointment of Senior Executive Engineer was made. .

For the greater part of the year only one of the two posts of Geologist was filled and in order that the siting of the bored wells should keep ahead of the drilling rig movements it was necessary to employ a consulting ground water geophysicist for one month early in the year.

IV. Staff

The establishment. and staff position for the year is shown on.the list at page 21 of this report. The Works Supervisor post again remained in abeyance and the'new post of Senior Geologist created in July, 1960, was kept in abeyance from its creation, Two Field Assistants of long service were selected for training with a view to their becoming eligible for promotion to the Hydrological Assistant grade. Initially they w,ere promoted to Senior Field Assistant posts which are held against the establish-ment of the Government's Joint Training Pool. At the same time two Hydrological Assistant posts were put in abeyance,

The total senior staff and Grade III junior staff establishment excluding posts in abeyance and including the Training Pool posts numbered 35. Taking 35 man-years as 100 per cent. total establishment staff time, an analysis of the staff situation gives these results for 1960:

Productive time Vacancies time Vacation leave Local leave Sick leave

Per cent, 75.9 10,5 10.3 2.2 1.1

A more detailed analysis shows that the productive time for the Water Develop-ment Engineer staff was only 35 per cent, and for the Hydrological Assistant staff was only 57 per cent,

V. Buildings

Towards the cnd of the year the Public 'Norks Department carried out part of the work required for the development of the new \Vorkshops and Stores area which is adjacent to the existing Stores Depot, The area was fenced, the roads laid out and two latrine blocks were built. The area has been brought into part use for open storage of bulk materials and for parking of equipment, but it needs further develop-ment before it is of any great value.

To assist the hydrological survey field staff in their work a new rest house was built at the Shire l~iver gauging station at Liwonde and temporary housing for a survey team was built at Mlolo in the Lower Shire I~iver area.

VI. Equipment, Plant, Vehicles and Watercraft

Following Boards of Survey two fiat-bottomed boats and the motor launchJeannie were declared unserviceable, A design for a plywood dinghy was selected and one was built in the Department's workshops, It was found suitable for the hydrological survey work and as a result two more were built. Each boat was equipped with a light structural steelwork boom of improved design from which a current meter could be suspended while making discharge measurements,

Three sets of current meter traverse gear and seven Ott waterlevel recorders were received for use in the hydrological survey,

The laboratory equipment was augmented by an aperiodic air damped balance, while the Department's workshop facilities were improved by the addition of an air compressor and a pillar drilling machine,

One Gunn-Bellani radiation integrator was purchased for use in evaporation research work, and a resistance test panel for testing the resistivity instruments used in geophysical surveying was also purchased,

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Once again the Workshop staff are to be commended for maintaining a high standard of serviceability of the Department's plant, vehicles and equipment through-out the year. Over and above the normal maintenance and repair work, which included several complete overhauls, much useful fabrication work was undertaken in addition to that already described. Three wells maintenance trucks were fitted with collaps-ible lifting booms and with canopies, two caravans were completely refitted, a special trailer for transporting casing was completed, a 400 gallon water tank trailer was built, and there was the normal year's output of about 200 bush pumps.

VII. Hydrological Survey

1. GENERAL

Owing to resignations and vacation leave only 57 per cent. of the established Hydrological Assistant staff was available dming the year. It has become increasingly difficult to rccruit expatriate staff to these posts and during the year it was decided to train experienced and suitably qualified locally based staff to fill them. After a competitive interview of candidates, a number of whom were from the Department, two Field Assistants possessing considerable field experience werc selected and posted to headquarters for one year's probationary training prior to appointment as trainee Hydrological Assistants. These officers now come under the full time supervision of professional and technical officers as well as assisting in the field work in the Southern Province. During the critieal staff shortage that occurred towards the end of the year in this province, these officers were able to contribute much to the routine work of the hydrological survey.

The main emphasis of the work during the year has been the consolidation of the existing cover of the hydrological survey by improvement of the gauging stations by constructing control works, weirs, automatic water level recorders aud cableways. However, in the Southern Province, a limited extension of the survey was made in the Chilwa-Chiuta-Amaramba lake complex which area has hitherto been largely neglected owing to effort having been concentrated in the important Lake Nyasa-Shire drainage area. In the Northern Province the cover of the survey was improved by establishing a permanent base for a field party at Nchenachena.

In the course of this work a number of new stations have been opened and a number closed, the net result being an increase of 6 new regular gauging stations, 4 regular gauge height stations and 1 evaporation station. Total numbers of the various types of stations which were in operation at the end of the year were:

125 H.egular Gauging Stations 25 Measuring Weirs 47 Regular Gauge Height Stations 12 Automatic Water Level Recorders 7 Automatic Recording Rain Gauges

32 Evaporation Stations

A large number of current meter discharge measurements were made at miscel-laneous sites, mostly in connection with specific water supply schemes, and of 2,633 current meter discharge measurements made during the year, 971 were made at such miscellaneous sites. The number of miscellaneous measurements continue to increase to meet requests for data from various consulting engineers and other private bodies engaged upon water supply, reclamation, hydro-electric and irrigation investigations.

In June a six-day informal conference on hydrology was held at the headquarters of the Department at Blantyre. The conference was attended by twelve delegates from East and Central African territories and by a number of observers. Visits were made to places of hydrological interest in the Southern Province and discussions were held on various aspects of hydrological work. Of the papers read at the conference,

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two were prepared by the Department and these were entitled" Some Points of Interest on the Hydrology of the Shire River" and "The Measurement of Sub-surface Flow in a Sandy River Bed in Nyasaland ".

2. RAINFALL

For the second year in succession the rainy season was a poor one, the rainfall over the whole Protectorate only averaging 85 per cent. of the long term mean. In the Northern Province the rainfall was normal to just below normal, in the Central Province it was above normal as a result of a cyclone traversing this area in mid-December when falls of up to 12 inches occurred in a single day, and in the Southern Province it was well below normal, seasonal totals being only between 60 and 80 per cent. of the long term mean.

Although the rains were, as in the two previous years, late in starting, there was widespread rain in December. In January, however, there was a marked change in conditions; the low pressure trough that normally develops over Central Africa at this time failed to do so and the upper air was much drier than is normal for this time of the year. This condition persisted and there was no widespread prolonged rain throughout the season until the end of April, except on four separate occasions. From late April, however, there was a strong influx of moist south-easterly air that brought widespread rain to all areas, but it was too late in the season to make any appreciable difference to the water resources.

On 10th December, 1959, cyclone" Colleen" crossed the coast at Mocimboa in Portuguese East Africa where it caused some damage, and then travelled south-westwards towards Nyasalancl. By noon on Ilth December the cyclone was centred over Fort Maguire but during that night it deepened over the Lake, turned northward and then westward over Kota Kota and along the course of the Bua valley into Northern Rhodesia where it gradually filled up. Eainfall during the passage of this cyclone was generally heavy; 12 inches fell at Kota Kota, Do-wa and Likoma Island and 6 inches at Lilongwe and Fort Manning.

3. EVAPOIlATIO:-i

The table on page 25 shows the evaporation as measured at selected stations during the hydrological year, and a comparison is made with the long term means. The figures shown are actual inches of evaporation from a standard screened pan and do not represent evaporation from a free water surface and research work is at present being carried out in order to determine the relationship between pan evaporation and free water surface evaporation under Nyasaland conditions. From the table it will be noted that evaporation, as measured from the pans, has been lower than average during the year, thus breaking an upward trend in evaporation that has prevailed since the dry season of 1957.

In the latter part of 1959 the evaporation pans at the Department's stations were painted black internally to conform with standard practice in East and Central African territories and therefore a direct comparison could not be made between new and old records of evaporation. However, as a result of studies made during the year a satisfactory relationship between the unpainted and painted pans was obtained and the old records have been adjusted to give equivalent black pan results. The mean evaporation figures shown in the table have all been amended on this basis.

To improve the network of evaporation stations throughout the country three stations were closed and four additional stations opened. The new stations are located at Nchalo beside the Elephant Marsh, Nkanda on the Lake Chilwa littoral, M

4, mVER FLOW

A schedule of river flow mfonnation for the hydrological year 1st November, 1959, to 31st October, 1960, is shown on pages 28-2fl and it will be seen that, for the third year in succession, flows were generally below average. Total recorded flows for almost the entire Southern Province and the greater part of thc Central Province were below average and in m.any areas of the Southern Province unprecedented minimum values as low as 1 per cent. of the average were recorded. Those areas seriously affected were the Zomba-Palombe plain, the Blantyre area and the western Shire valley. In this latter area there was no surface flow in any of the major rivers for nine months of the year and in the case of one river, the Tangadzi West, there was flow for a period of only four days during the year. In the Northern Province, as a result of heavier rains, the majority of flows were above average. The Eiver Shire Flow Information table on page 26 shows that the total flow at ChirOlno for the year was less than that recorded at Maganga further upstream. This is thought to be dne to evaporation losses in the Elephant Marsh exceeding the inflow from tributaries and rainfall over the area.

The severe depletion of flow in almost all rivers in the Southern Province is attributable to the cumulative effect of the low rainfall for the past three years. In some cases, however, it seems probable that this is not the only factor responsible. With the steady increase in population on the land, more land is being brought under cultivation and being subjected to malpractices whose ultimate effect is a steady deterioration in the country's water resources.

Lake Nyasa reached a maximum level of 1,556.5 feet on 15th 1VIay, 1960, which was 0.6 feet below the maximum reached in 19;3fl, and 3.9 feet below the very high level reached in May, 1937. The mean daily flow of the Shire Eiver at Liwonde during the period 1st November, 19;39, to 31st October, 1960, was 9,900 cusecs.

Tabulated data and hydro graphs in this report cover many of the stations in-cluded in previous reports so that comparisons can be made. In considering the mean values the short period of time over which average figures to date have been deter-mined should be taken into account.

5. SUSPENDED SEDIMENT MEASUHEMENTS

As. has been the practice since HJ52, suspended sediment samples were taken during the year at all regular gauging stations. During the wet season samples were taken whenever a discharge measurement was made, but during the dry season samples were taken less frequently.

The snspended sediment data so obtained was used in conjuction with the rele-vant flow hydrographs and the total annual snspended sediment load for each river was expressed firstly in tons per square mile and then as the" silt factor" which is the ratio of the total annual suspended sediment load in tons to the total annual water flow in acre feet (tons per acre foot). The silt factors for the year 1959/60 are shown in the table on page 30 as are the results for the previous years back to 1951/52 and the long term means of the factors. It may be observed that the factors are in general low for 1959/60 and this is attributable to the low rainfall and river flows experienced.

6. CONSTHUCTION wonK

The Department has little works capacity, and building work for the hydro-logical survey is necessarily limited. In spite of this a comparatively large pro-gramme of work was completed this year largely as a result of co-operation by the Forestry Department which undertook the constmction of certain stmctures on Zomba Plateau where they have well-established works facilities.

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Three gauging weirs were built during the year, two on the upper Mlungusi tributaries on Zomba Plateau and onc on the Chitakali Stream on the lower slopes of Mlanje Mountain. The first two weirs were erected so that accurate data could be obtained for catchment studies at present being undertaken as part of the research programme, and the third was built to obtain hydrological data for a proposed hydro-electric scheme on a stream where it was impossible to establish a regular current meter gauging station owing to the steep, broken and boulder-strewn nature of its course.

Four automatic water level recorcIers were installed on specifically de:;;ignecI structures at three weirs and at one controlled gauging station. One of these recorders, ,1 Leupold and Stevens long term type, was installed at the gauging weir on the Chambe plateau of Mlanje Mountain in order to obtain more accurate run-off data from an afforested catchment. The structure on which the recorder is supported is canti-levered from a rock face and was pre-fabricated in the Department's workshops, dis-mantled, and transported by cabJeway and porters to this remote location on the mountain and there erected. At the end of the year a further recorder installation was half completed at the Lilongwe gauging weir, work having been postponed owing to high water conditions.

Concrete control works were built at two regular gauging stations in the Southern Province as part of the general gauging station improvement programme.

During the latter part of the year three sets of traverse cable gauging gear with steel towers were delivered from the manufacturers in the United Kingdom and by the end of the year one set was installed and placed in operation on the Luehenza River over a span of 150 feet.

7. SUHVEY WOEI(

Minor site surveys for hydrological installations at nine gauging stations were carried out and post-flood surveys of river reaches were made at four gauging stations.

8. EESEAECH WOEK

The Department has no separate organization for research work but work of this nature is undertaken as part of the routine hydrological survey. During the year three research projects were undertaken which were:

(i) Evaporation measurements from standard pans were studied with a view to establishing a relationship between these measurements and potential open water surface evaporation as determined by the Penman equation. Observations were made and continue to be made at nine stations in various parts of the country where the wind-speed, temperature, humidity, sunshine hours and/or radiation are also measured. This investigation is being carried out in liaison with the East African Agriculture and Forestry Research Organization.

Calibration tests between Gunn-Bellani radiation integrators and standard evaporation pans were continued with some success, and investigations were carried out into the effect of the wire mesh screen and the black painting of the interior of the pans on evaporation pan measurements.

In accordance with a resolution made at the Informal Hydrological Con-ference, three Class "A" pans, which are the World Meteorological Office standard, were installed for comparison with the pan in general use by the Department.

(ii) Tests on the reduction of evaporation from open water surfaces by the use of a monomolecular film were carried out on a water supply reservoir near Blantyre throughout the dry season from April to November, the main object being to gain experience in the technique of spreading and maintaining an

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effective film on the watcr surface. Various trials were carried out using cetyl alcohol in pellet form, as an emulsion and in solution with various solvents. A solution of 25 gm. of cetyl alcohol in a litre of commercial paraffin was found most suitable and was adopted for the majority of the tests. This was introduced onto the surface of the water at a rate of 3 litres per acre per day by means of specially manufactured tanks having a drip fecd attachment which were placed around the perimeter of the reservoir. A floating type dispenser was also employed. Althongh considerable experience was gained in the spreading and maintenance of the film no finn conclusions on the effectiveness of the film as an anti-evapora-tion agent were arrived at, mainly as a result of difficulties experienced in the determination of the water balance of the reservoir. This investigation is being continned.

(iii) Long-term projects to study the rainfall-runoff relationship on two catchments recently afforested and to be afforested on Zomba and Mlanje mountains were initiated. During the year two gauging weirs, three automatic water level recorders, ten rain gauges, and other instruments for the measurement of evaporation, wind-speed, sunshine hours and temperature were set up, and observations commenced. Data on topography and vegetation on these catch-ments was collected with the co-operation of the Forestry Department.

VIII. Water Licences During the year 15 applications for water licences were received, of which 8

related to abstraction of water from streams and 7 to impounding water by dams. These were investigated and reports made. In addition 10 cases of renewal of water licences were investigated and reported upon. At the end of the year there were 62 water licences extant, the majority of which run for five year terms though some few are valid for longer periods.

In March, following the poor rains and in view of the shortage of the water supplies in the Blantyre-Limbe area, it was foreseen that private persons in the area would wish to drill bored wells to guarantee their own supplies and that if this were allowed to proceed uncontrolled the water resources available to the Mudi River Water Board for the public supply might become harmfully reduced, and that the ground water reservoir might become so depleted as to reduce the yield from. existing private bored wells. Accordingly in May, by a notice in the Gazelle, the Governor in Council declared that in terms of section 17 (3) of the Natural Resources Ordinance the Blantyre-Limbe Town Planning Area had become an area in which the underground water supplies were in danger of being undnly exhausted by reason of the extraction of water therefrom and thereafter the drilling of boreholes in the area was permissible only under licence from the Southern Province Natural H.esources Board. Appli-cations were received for licences for the sinking of 17 bored wells and 14 licences were granted in respect of a total of 16 bored wells. The Department was the advisor to the Natural Resources Board in the matter of the applications.

IX. Dam Subsidy Scheme New regulations for the Loans and Subsidies Schemes for Nyasaland Fanners

came into effect from 1st April, 1960. The proportion of the cost of dam and weir construction eligible for subsidies was raised from one third to one half and the limiting amount of the subsidy was raised from £720 to £1,000. The site investigation and design of dams having a planned depth of water of less than 15 feet became the responsibility of the Department of Agriculture, leaving only the higher dams as the Department's responsibility. As a result the Department had rather less work than usual in connection with the dam subsidies scheme: during the year designs were produced for five dams and one weir, and contract documents were produced for the construction of three dams; four dams were completed, built by contract, and one weir was completed.

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X. Advisory Services on Water Development

1. GENERAL

The hydrological records kept by the Department are, in general, freely available to the public. In addition the Department, within the limits set by staff availability and the requirements of other work, is able to advise other Government Departments and the public on hydrological and hydraulic engineering matters. Advice is usually given in the form of a report, and reports for Government agencies are usually in considerable detail and contain specific proposals for development, while those for non-Government agencies are less detailed but aim to afford sufficient information for the best line of development to be selected and for consulting engineers or manu-facturers of special equipment, if appointed, to see what is involved in the proposed development. During 1960 advice or data was supplied for a variety of schemes concerning hydro-electric, land reclamation, irrigation, water supply, drainage and harbour works.

The main work of the Gcologists of the Department is the siting of bored wells for rural water supplies. Their services are also available however for locating ground-water for the needs of other Government Departments and for the public .. The work of this nature which was done in 1960 is described in the well boring section of this report.

2. HYDRO-ELECTRIC SCHEMES

Hydrological data was supplied to the Nyasaland Electricity Supply Commission and the consulting engineers appointed by the Federal Power Board, Messrs. F. E. Kanthack and Partners, in connection with schemes for providing hydro-electric power for Mzuzu and Lilongwe using the water of the Luchelemu and Linthipe Rivers respectively.

Hydrological data was supplied to the Federal Ministry of Power, the Tanganyika Government andl\Iessrs. F. E. Kanthack and Partners in connection with the Nkula Falls hydro-electric scheme. This scheme, the purpose of which is to provide power for Blantyre and district, is of interest to the Tanganyika Government in that it requires the control of the Shire River, the outlet to Lake Nyasa, and therefore could influence the Lake levels and affect the Tanganyika shores of the Lake. Arising from the consulting engineers' report on the scheme the Department had discussions with the consultants on the hydrological aspects of the project.

A report on the hydro-electric potential of the Nswadzi River was prepared for an estate in the Cholo District.

3. LAND liECLAMATION AND IHRlGATION SCHEMES

Hydrological data on the Shire Valley continued to be supplied to the consulting engineers for the Shire Valley Project, Messrs. Sir William Halcrow and Partners.

The report of Messrs. NEDECO, the Dutch firm of consultants appointed by the Nyasaland Government to advise on reclamation of the Elephant Marsh, was received, and subsequently there were further discussions between the Department and the consultants on the hydrological and engineering aspects of the report.

Reports were made for the Department of Agriculture on the rice-growing potential of land on the Lake Chilwa shores and at Mlolo in the Lower Shire River area, and on water supplies for tobacco nurseries for African trust land tobacco growers in the Southern Province. In co-operation with the Department of Agri-culture, work was started Oil an irrigated rice scheme at lVIlolo, but had to be dis-continued due to a withdrawal of support for the scheme by the villagers.

V\

Hydrological measurements were made in connection with a report to be made to the Secretary for Natural Eesources on the rice-growing potential of the Lifidzi area on the shores of Lake Nyasa.

Hydrological data for tea irrigation schemes was supplied to two estates, one in the Cholo area and the other in the Northern Province. A report setting out proposals for ,1 tea irrigation scheme was made for another estate in the Cholo area.

4. WATER SUPPLY SCHEMES

In general, domestic water supply schemes for Government stations are the concern of the Public Works Department but the ';Yater Development Department advises on those schemes which are not primarily for the supply of domestic water.

A scheme was drawn up by the Department for the supply of water from a borehole for domestic and irrigation purposes for the Department of Agriculture's station at Makoka. In addition to preparing the design the Department sunk the borehole as part of the normal boring section work and also installed the pumping plant. Another scheme was drawn up for the supply of water for irrigation and for coffee processing at the Department of Agriculture's station at Bvumbwe. The work on this scheme included the design and preparation of contract documents for a dam to form an impounding reservoir on the Chisowanu Stream..

For the Department of Veterinary Services a report was prepared for a small hydram water supply scheme for stock watering at their Mikolongwe Station, and a design for the supply from a dug well for irrigation and domestic purposes for their Malema Station, near Karonga was also prepared.

The Public Works Department have appointed Messrs. Brian Colquhoun, Hugh O'Donnell and Partners as consulting engineers to advise on water supply schemes for Cholo, Chiradzulu, Karonga and Zomba. Hydrological data was supplied to the consultants in respect of all of these schemes. For Chiradzulu a report was prepared on the general water resources of the area, both underground and surface, and the preparation required extensive geophysical surveying. For Cholo and Zomba, stream gaugings over and above the normal routine gauging were necessary and some new gauging stations had to be established.

Hydrological work was undertaken for the Public Works Department in connection with their proposals for water supply schemes at Fort Manning, Ncheu and Mwanza. Data was supplied for Fort Manning and Mwanza, which for the latter was in the form of a report on the flow of the M wanza Eiver. Flow data for the Nkhande Eiver was collected for the Ncheu scheme and a new gauging station has been established on the Bua Eiver to give flow data for the Fort Manuing scheme.

Hydrological data was supplied regularly to the Mudi H.iver Water Board, the BJantyre-Limbe township water suppliers, and intennittently to Messrs. Maggs and Keeble, the consulting engineers for the Lilongwe Town Water Supply Scheme.

Brief reports on domestic water supply schemes were made for two missions in the Southern Province and a rather more detailed report was made for the domestic water supply for an estate in the Cholo District.

5. FLOODING AND DRAINAGE

As a result of the low rainfall during the year, flood warning action for the Lower Shire area was not needed though the usual watch was kept on the H.uo H.iver and Shire Eiver water levels.

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Hydrological data was supplied to Messrs. Sir WiIIiam HaIcrow and Partners, consulting engineers to the Government, for the investigation of the problem of flooding and shore erosion at Karonga.·

Estimates of flood flows at bridges and culverts were made for the Public Works Department for five sites and for the Nyasaland Railways Limited for four sites. Hydrological data was supplied to the Public Works Department in connection with the Luweya River bridge and the Chia Lagoon ferry.

6. HARBOUR WORKS

A preliminary scheme was prepared for the Game, Fish and Tsetse Control Department for the provision of a jetty at Kachulu on the shores of Lake Chilwa to facilitate the unloading of the fishing boats.

XL Well Boring

1. GENERAL

152 electrical resistivity surveys were carried out resulting in the selection of 136 bored well sites. Of these surveys 98 were for African village water supplies, 26 were for other Government Departments and 28 were for private concerns.

no of the sites selected were drilled by Government drilling machines and one site was drilled by a Departmentally manufactured hand powered rig. Certain sites selected for the Public Works Department were sunk by a drilling contractor but detailed results of this drilling are not yet to hand. The number of sites drilled by the Department was less than in previous years due to an increase in the number of large diameter bored wells sunk, to a shortage of drilling staff late in the year and to a greater distance between sites than hitherto, particularly in the Northern Province, together with the need to drill to greater depths to obtain supplies.

One Geologist secondcd from the Geological Survey Departmcnt was engaged on siting bored wells by geophysicaJ survey methods throughout the year. He was assisted by a consulting ground water geophysicist for one month during January and February, and by a Geologist, also seconded from. the Geological Survey Department, from November.

Bored wells which failed to give adequate supplies and on which no pumps were fitted totalled four. Two of these were abandoned due to drilling difficulties and in the other two insufficient water was fonnd. One of these failures was successfully redriIled. Three wells each yielding less than 100 g.p.h. each, and which cannot be classed as successful were fitted with pumps in view of acute water shortages.

2. ANALYSIS OF BORED WELLS DRILLED, 1960

Prodllctive boreel \\'ells (includjng 3 ~'icldjng less than 100 g.p.h.) Non-productive borccl wells Total bored we1ls Footage productive bored wclls Footage non-productive bored \\'Clls Total footage Total tested yie1(1 Average tested yicJcl-----producti\·c bored wells Average depth-productive bored wells Percentage success .. Bored wells to be mechanized Climax pumps fitted Bush pumps fitted Bored wells c1canc(l and deepellcd Footage deepened

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107 4

111 14,517 ft.

833 ft. 15,350 ft. 70,589 g.p.h.

660 g.p.h. 136 ft. 96% 9

13 85 13 48

The numbers of bored wells drilled in particular Districts are shown in the following table:

District

Blantyrc Chikwawa Zomba Port J1craJ cl jV!lanjc Cholo Fort] uhnston

Kasungu f{ota. ](uta DOWEL

J-ilongwc )J"cheu

,\Izimba .Karonga H.l1mpi

TO'L\LS

I 3. SOUTHERN PROVINCE

24 7 ij

4 J 1 I

Il \l 7 ,I I

l()

8 7

107

I -

I

I

I

2 J

44 wells were sunk in the Southern Province, mainly in the l3lantyrc District, by two drilling machines. Onc of these holes was sunk in Fort Johnston District by the hand boring-rig.

(a) Elantyre District All 24 wells sunk were successful, most yields being between 600 and 1,000 g.p.h.

The lowest yield, 120 g.p.h. was at Nkupa village where the only available site was in the margin of a dambo. Six sites in N.A. Chigaru's area gave satisfactory yields of between 650 and 900 g.p.h., all of them being sunk in weathered basement gneisses.

N.A. Symon's area benefited to the extent of four bored wells, all located in the area between the western escarpment of the Rift Valley and the Lisungwe River. Here, great thicknesses of Rift Valley sediments appear to be present, and the location of suitable bored well sites by geophysical surveying was not difficult. The well at Mpatamoyo yielded hot water, indicating that a deeply penetrating weakness associated with the Rift had been struck. It is surprising that this well was only sub·artesian, the water rising but a few feet after being encountered. Although all the N.A. Symon wells were within two miles of each other, only the one yielded hot water.

After extensive traversing the consultant geophysicist selected three sites in the Mwanza Sub-District and all proved successful.

(b) Zomba District Limited work was undertaken in the Zomba District but the programme originally

drawn up in 1959 was completed. Three wells were sunk in N.A. Msamala's area which lies wholly in the floor of the Rift Valley and all were successful. At Songani Trading Centre a narrow zone of low resistivity was located and the well sunk gave an adequate yield of 675 g.p.h.

(c) Chikwawa District Village bored wells were drilled only in N.A. Ngabu's area where four were

successfully sunk. As is usual in the Lower River area, considerable difficulty was experienced by the geologist in finding sites which did not have saline water. Resis-tivities commonly fall below 0.5 ko.c. and in Irtany cases it was impossible to locate

16.

Boats huilt by the Department for use in stream gauging

The ne\\' rest-hollse at the gauging station on the Shire Hiver at Li"'onde

~\n artificial control structure of catenan- form at the gauging station on the l,uchcnza. T~ivcr

}fcasnring the Luch:l1za Hiver 1l0\\" ll~ing current meter travcr::;e gear

Complete gauging station on the Tangadzi N.i\'er comprising a part natural, part artificial control, staff gauges and water level recorder

Meteorological Station set up by the Department on Zomba .Plateau for ::V[ulllngllzi Catchment Ecscarch

,Vater level recorder and nlcasuring "\Yeir on Chapaluka Stream for Chambe rlateau Catchment H.esearch

Sinking a 1>orc1101c \\·ith the lEl..ncl boring-rig

an aquifer with a resistivity above this value. Although water from all the Ngabu wells showed some salinity, none was so bad as to be unpotable and pumps were fitted in all cases. Difficulty was also experienced by the driller owing to the presence of very fine sand and silt which made it impossible to withdraw the 6 inch diameter casing and replace it by 4 inch as is the normal practice.

(d) Port Herald District

Two wells were sunk, one at N.A. Tengani's Court and one in N.A. Ndamera's area, and both were successful, although fine sand and silt were encountered in both cases.

(e) Fort Johnston District

As a part of a drive to encourage self-help among rural communities a hand powered boring machine was constructed by the Department and Fort Johnston District was selected as being a suitable area in which to test both the mechanical capabilities of the apparatus and the attitude of villagers towards self-help projects. The equipment was used at two villages and although the people showed interest in the work they displayed no willingness to help. The first site was sunk to 52 feet in 19 days by a Water Development crew of seven. A 115eful supply was obtained and a pump was fitted. A second hole was started at another village but after 5 days work when the hole had been sunk to 31 feet it was abandoned as it was evident that no self-help was forthcoming. The lack of co-operation in this village was surprising since the women of the village had at that time a return walk of four or five hours to fetch water.

4. CENTRAL PROVINCE

Only one machine was employed in the Central Province and 32 bored wells were completed mainly in the Kota Kota, Kasungu and Dowa Districts.

(a) Kasu.ngu District

Ten wells were sunk for rural supplies and one at the School for the Blind. Yields were not entirely satisfactory. Only two wells produced over 500 g.p.h. and two gave a mere 60 g.p.h. Pumps were fitted on the latter two, however, because of serious water shortage. Although the depth of weathering of the hornblende biotite gneisses of the Kasungu District is often substantial and good yields might be expected, the low yields actually obtained were probably due to high clay content of the decom-position products and a low rainfall. In addition it is difficult to locate satisfactory sites by measuring electrical resistivities owing to the thickness and sandy composi-tion of surface layers. In several cases insufficient voltage was available to the Geo-logist and depth probes were impracticable. All work was confined to the areas of N.A. Mwase and N.A. Kaluluma. The well at Chisazima although tested originally at 720 g.p.h. failed after two months and was deepened by 48 feet after which it produced 288 g.p.h.

(b) Kota Kota District

Three wells were sunk in the Visanza hill area and six in the Lake-shore area. Two Visanza sites gave very poor yields of 50 and 150 g.p.h. but in view of the water shortages which prevailed pumps were fitted. The Lake-shore sites were more satisfactory but yields were not as high as is usual for Lake-shore areas, being between 240 and.720 g.p.h.

17

(c) Dowa District Seven wells were completed in the Salima Sub-District in the soft sands and silts

of Lake Nyasa. One of these was sunk for the Salima Town Council to replace a well which had been taken over by the Federal Government for use by the Salima Asian School. All yields were satisfactory.

(d) Lilongwe District All the drilling in this district was undertaken for Government Departments.

Drilling difficulties were experienced at the Chitedze Agricultural Station where work had to be abandoned on one site because of caving in and consequent inability to obtain sufilcient yield. A second site on the station yielded 2,240 g.p.h. Wells drilled at Kabudula Health Unit and Kasiya I)olice post both yielded 660g.p.h.

(e) N clzeu District One well originally commenced III j\J5H was completed at Mpira School and

yielded 360 g.p.h.

5. NORTHERN PROVINCE One machine worked in the Northern Province until September and this was

joined by two others in March and June. :35 wells were sunk of which three were unsuccessful.

(a) M zimba District N.A. M'mbelwa's area gained seven Hew wells with yields which varied between

200 and 900 g.p.h. Generally speaking the whole of the south-west of the Mzimba District, which takes the form of an old, deeply weathered surface, is very well provided with ground water and bored well siting is not difficult.

Three wells were sunk in the area of Chief il1zukuzuku and all gave adequate yields, as did two in N.A. iVIabulabo's area.

In the northern part of the Mzimba District one well was successfully drilled in weathered biotite gneiss and yielded 900 g.p.h.

(b) Karonga District The machine which had been working in the Karonga Lake-shore area in 1959

remained there until September when the driller resigned. Eight village wells were completed there though extreme difficulty was experienced in driving casing through the unconsolidated lake deposits. The water table in the section of the Lake-shore appears to be extremely variable laterally. Near Deep Bay within a distance of about three miles it changes from 22 feet below the surface to 182 feet although the gradient of the ground surface is negligible. All yields were satisfactory, varying between 340 and 1,200 g.p.h.

(c) Rumpi District Seven wells were completed in the areas of N.A.s Chikulamayembe and Katumbi.

Yields were all above 500 g. p.h. and were particularly good at Lukali and Chiwaya which lie in the Henga Valley which is probably underlain by decomposed Karroo iVIudstones and Shales.

6.. WORK FOR GOVERNMENT DEPARTMENTS

Twenty-six geophysical surveys were undertaken for other Government Depart-mentsat)d29 bored well sites selected. Ten of these were drilled by the Department's machines and more were sunk by contractors on behalf of the Public Works Depart-ment.

18

Work for the Federal Government was undertaken at Palombe, Rumpi, Namizana, Nsabwe and Malosa and bored well sites were selected in each case. Only at the site at Rumpi, at the proposed location for a leprosarium was a borehole drilled but its tested yield of 480 g.p.h. was considered insufficient for the project and the site was abandoned .

. ~TheAgricultural Department requested surveys at Chirimba, Mbawa, Makoka, Masambanjatiand on the site of a proposed Farm Institute near Mbawa. Sites for bored wells were selected at all these localities except Masambanjati where a dug well was recommended. The Chirimba, Makoka and Mbawa sites were the only ones drilled and gave very satisfactory yields, but the well at Mbawa gave water too saline for domestic use.

Surveys were made on behalf of the Nyasaland Police at Bangwe, Kasiya, Champila, Kafukule, Namitete, Ngabu and Linthipe. No suitable bored well site could be located at Kafukule.

Five investigations for township supplies were made at Chiradzulu, Mwanza, Chikwawa, Fort Manning and Kasupe, all in close co-operation with the Water Branch of the Public Works Department. Bored wells were sunk by a contractor at Chiradzulu, and by the Department at Mwanza and Chikwawa. The latter well is worthy of particular mention in that it had to be pumped and surged for 26 days before all the very fine mica had been drawn from the aquifer immediately surrounding the casing.

Other surveys were made for the Forestry Department at Chongoni and for the Game, Fish and Tsetse Control Department at Mwabvi Game Camp. A bored well was sunk at Mwabvi.

7. GEOPHYSICAL SURVEYS FOR PRIVATE CONCERNS

Applications for geophysical surveys on private land increased with the introduc-tion of a revised Loans and Subsidies Scheme for Nyasaland Farmers. Under the new scheme any bored well sunk, sited by a Government Geologist on a bonajidefarm, is subsidized by Government to an extent of 30 per cent. at least. Twenty-eight surveys.\vere undertaken including six for mission stations.

As a result of the water shortage in Blantyre-Lil'nbe, a series of wells was success-fully sunk by the Mudi H.iver .Water Board on sites selected by the Department's Geologist.

As far as is known two of the above 28 sites failed to give satisfactory supplies.

8. DRILLING

The full complement of six drilling rigs was working, apart from breaks for drillers' leave, until September when one driller resigned.

Apart from minor changes two machines were engaged in the Southern Province, one in the Central, and three in the Northern Province although it proved difficult to keep the latter fully occupied due to the inaccessibility of certain Northern Province sites.

9. WELLS MAINTENANCE

Five wells maintenance units continued in operation throughout the year as in the previous year. The centres of operation of the units were Chiromo, Blantyre, Balaka, Lilongwe and Mzimba, and the number of bored wells being maintained at the end of 1960 by each of these units were Ill, 337, 250, 245 and 109, respectively, totalling 1,052.

19

All five units made their routine tours of inspection during the year and carried out repairs and replacements where found necessary. The Blantyre and Balaka units which have the most wells to maintain, found some difficulty in covering their areas fully and towards the end of the dry season many requests for repairs came in which could not be attended to with the prom.ptness which is desirable. It is apparent that the numbers of bored wells which each of these units are maintaining are becoming too great for efficient working and that an additional unit will soon be needed to relieve them.

An Edeco light drilling rig was engaged in cleaning silted bored wells in the Lilong'\ve, Ncheu and Dedza Districts throughout the year.

10. BOREHOLE SUBSIDY SCHEME

With effect from 1st April, 1960, the Loans and Subsidies Scheme for Nyasaland Farmers was varied in several respects, one of which was that the scheme by which rebates were paid on the cost of unsuccessful boreholes was changed to a scheme for subsidizing the cost of boreholes whether unsuccessful or not. The minimum subsidy is now assessed at 30 per cent. of the drilling charges and higher rates of subsidy are paid for boreholes of poor yield according to their degree of unsuccess. As a result of this change and also, probably, as a result of the water shortage which prevailed in the Southern Province during the year, greater interest was shown in the scheme and ten applications for subsidy were received. On one farm no suitable site for a borehole could be found. At the end of the year three of the nine remaining borehole sites bad been developed and the boreholes approved for subsidy.

XII. Conclusion

Although the tempo of work has been somewhat slower as a result of staffing and other difficulties described herein, the year 1960 can still be said to have been one of progress in the Department. A gratifying aspect of the work has been the increasing demand for advisory services which the Department can offer.

In keeping with the times a start has been made in the training of Africans for senior technical posts and it is confidently hoped that an increasing share of respon~ sibility will be home by these local service officers.

Both senior and junior staff have shown a loyal and co-operative spirit in their duties and this has been much appreciated by the writer.

BLANTYRE, March, 1961

20

E. W. LATHAM Director of Water Develop1hent

STAFF LIST 1960

Senior Staff and Grade III Junior Staff on the Establishment

ADil-IINISTRATIVE

Director

Senior 'Executive Engineer

Secretary / A eCOll n tan t Departmental Assistant

Stenographer (I)

Draughtsman lVlcchanical Supervisor (1)

Senior Storekeepers ('2)

E. Vi/. LATHA:>I, 13.5C. (ENG.), A.e.G.I., A.M,Le.E., A.:i\LI.\V.E. On v8.cation leavc from 27-7--60.

R. G. GALE, B.se. (ENG.), Took up appointment Director from :27-7---60.

~\. E.VANS

J. 1-1. NAPlER, F.E.:\.S.

A.rI'Ll.c.E" A M.LW.E.

on 1 ~2·-60, At-ting

l'I'1ISS i'd. N. HYL:\>;n, on vacation leave from 1 [5·-10- 60. ::\11155 A. COLE from 11---l()--60.

\V. H. STRUDWICK T. E. J O~ESJ on vacation lea vc from 29 ·9,",60. J. IVlcLEAN, took lip tcmporaT~r appointment from

12··9-1\11. }f. 1." N :H'I ,\ H \\' A B. J. N:\i\iB,\, on leave pending transfer. .'\\\,

''!) w

No. I

, ~, '

District and Locality

--~i-·--·

Southern Province Blantyre District

J 40 l'uchila Court W 187 Kachingwe W186 Nkupera W185 Mpezeni W183 Namonde :lIarket W 184 Ntiyana .. W 196 Chirimba Agric. Station J 30 Neno Boma J 31 .Johnathon J 32 Nangombe

W206 Makata's Court .. W178 Ngwaya W230 Chiwaya W 180 Masulani

W 179 Monekera W241 Morson W242 Mpatamoyo W243 Nkase .. W244 Nankudwe W245 Thamanda W271 Mwanza Township J 46 Daya .. J 38 Mbulumbuzi Court J 48 Mombezi Court ..

Zomba District W 177 Songani Trading Centre E 300 Balaka Township J 6 Toleza J 5 Kwitanda J 4 Mwanga W 169 Makoka Tobacco Farm

Fort J ohnston Distrwt Z 200 I Mpembena.

P(YJ't Herald j)i$trict W 249 Tengani Court W 250 Chinsungwe W277 Muona Mission ..

W251 Chiromo Asian School

Depth Yield in ft. G.P.H.

101 900 101 500

93 120 160 480 110 450

95 640 151 1,150 134 1,000 172 480 190 800 118 960 154 720 154 652 120 650

178 720 104 800 104 820 174 800 175 800 126 850 183 240 117 240 117 626 153 450

99 675 312 3,230 130 2,000 150 400 125 900 142 1,542

52 100

162 1,200 231 600 153 100

107 972

TABLE OF BORED WELLS DRILLED IN 1960

Rest i I Sp. Res. t I Month Ileyel I RemMks "eology I lower Top aud Sp Res. la.yer bottom I wet zone Month of drilled (m , I K.Ohm wet zone K.Ohm survey feet) I Cm. (in feet) Cm. 1--1 I I

' 12) N.A. Nkalo Weathered Gneiss Feb. 30.4 10-40 1.6 Feb. Feb. 32 I N.A. Nkalo Weathered Gneiss 420 10-40 2.1 Jan. March 22 I N .A. Nkalo Dambo Sands and Clays 90 10-60 4.8 Jail. April 10 i N.A. Nkalo Weathered Gneiss Not Resolvable Jan. April 20 I N.A. Nkalo Weathered Gneiss 25 10-40 1.3 Jan. April 15 i N·A· Nkalo . i Margin of Dambo 13.5 10-20 1.5 Jan. it'Iay 5 ! Agnc. Dept.-mechamZedl"weathered SYenite 10.8 10-40 4.1 March .June 27 ! N.A. Mla.uli Biotite Gneiss 150 10-40 3.8 Nov. 1959 .Junc 108 N.A. Mlauli Weathered Gneiss 9.3 20-60 2.3 Nov. 1959 July 118 11!·A.l\:n~uli I Weathered Gneiss 5.7 20-60 1.4 Nov. 1959. July 14 N.A. Chlgaru Weathered Gneiss 900 40- 4.5 April August 75 N.A. Chigaru i Weathered Gneiss 130 10-S0 0.65 .Jan. August 851 N.A. Chigaru I Weathered "neiss 1.1 20- 1.1 July August 12 N.A. Chigaru ! Dambo Deposits over i Gneiss 640 0-40 3.2 .Tan. Sept. 85 N .A. Chigaru i 1Iargin of Dambo No Depth Probe .Jan. Sept. 48 . N.A. Chigaru I Weathered Biotite Gneiss No Depth Probe Aug. Sept. 45 N.A. Symon-liot water I Dambo Sands and Clays 1.0 20- 1.6 Sept. Oct. 110 N.A. Symon Sands and Gravels 5 80- 4.6 Sept. Oct. 95 N.A. Symon . Sands and Gravels 3 20- 3.0 Sept.

Oct. 78 N.A. Symon F Sands and Gravels 4 80- 4.0 Sept. Nov. 25 Township Supply P.w.D'1 Biotite Gneiss 480 10-60 2.4 Oct. Dec. 33 N.A. !lIpama Weathered Gneiss 320 15-40 1.6 Feb. Dec. 15 N.A. Jl.lpama Weathered Gneiss 324 10-40 1.62 Jan. Dec. 6 N.A. Mpama I Weathered "neiss 25 20-40 1.3 Feb. Jan. IS N .A. Chamba. . Sheared Gneiss 520 10-40 2.6 Dec. 1959 March 66 P.W.D. to be mechanized Drift over weathered gneiss 7.9 5-80 0.8 Dec. 1958 April 25 N .A. Msamala. Alluvium over Gneiss 19.2 20-60 4.8 Oet. 1959 April 42 N .A. Msamala. Alluvium over Gneiss 3.1 20-00 0.7 Oet. 1959 1I-1ay 52 N.A. Msamala , Alluvium over Gneiss 39 20-80 2.0 Oct. 1959 June 21 Agric. Dept.-mechanized: Quartz Felspar Granulite 198 10-50 0.9 Dec. 1959

I Dec. 18 S.N.A. Chimwala-Hand j

operated Rig i Lake Sediments No Geophysical Survey

Oct. 17 N .A. Tengani Thick Alluvium No Depth Probe Sept. Nov. 152 N .A. N damera Thick Alluvium 3.6 40- 3.6 Sept. Nov. 75 White Fathers Fine sands and clays 'over

basement gneiss 3.7 10-40 2.0 June Dec. 10 Federal Government Thick Alluvium No Depth Probe Sept.

TABLE OF BORED WELLS DRILLED IN 1960-(Contin",d)

[I ~-I 1 .' Rest lower Top and Sp. Res. )\'0. DistrICt and I .. ocahty Depth Yield Month 1 level 11 Remarks Geology layer . bottom wet zonel Month of

in ft. G.P.H. drilled (in . K.Ohm 1 wet zone I X.Ohm survey feet) I Cm. (in feet) Cm.

HD Ghikwawa District. I---! I ------1 163A Chi?-wawa. Tovmship . . 210 2,350 July '126 11 P.V{.D.-mechanized Clay, sand and gravel I No Depth Probe

W 201 Ap.nl Development Area. . 160 1,200 July 54 K.A. Ngabu Alluvium' I 1.5 40- . 1.5 April W 202 C_hlbembe 200 550 Aug. 4& N.A. Ngabu Alluvium 0.7 40- 0.7 April W 205 Ngabu Police Post 150 1,200 Aug. 40 i N.A. Ngabu Alluvium I 1.1 10-80 0.5 April W 203 Nsangwe 150 1,000 Sept. 61 ! N.A. Ngabu Alluvium 0.5 20- 0.5 April "\V 204 Konzer0 .. 140 1,000 Sept. 4-5 I N.A. Ngabu Alluvium ! 0.9 20- 0.9 April ,V 226 Mwabn Game Reserve 162 540 Oct. 17 I Game, Fh,h and Tsetse I

, Control Dept. Rartoo Sandstone and shale I 600 90-100 3 June Cholo District

J 28 Luchenza Asian School 113 730 Jan. 55 Fed. GOyt. -to be mechanized Weathered Gneiss 28.3 18-40 1.4 i Oct. 1959

lYflanje District 'N 151 1)alo111be Police Post 120 Nil Jan. Abandoned dry-P.W.D. Weathered Gneiss 38 10-60 2.1 Oct. 1959 W 181 l'alombe Police Post 130 250 Feb. 5 P.W.D. Weathered Gneiss 580 20-60 2.9 Jan.

Central Province Lilongwe District

W ] 1 () ()hitedze Agrieultural t'>!J Station.. 160 264 Jan. 39 Abandoned due to caving W -P.W.D. 'Yeathered Gneiss 2.7 40- 4.7 Aug. 1959

"YV 118 Chitcdze Agricultural Station .. 183 2,244- Jan. 38 P.W.D.-To be

mechanized "'Weathered Gneiss 5.9 20- 5.9 Aug. 1959 W 155 Kabudula Health Unit 150 MO Feb. 31 Fed. GOYt. Weathered Gneiss 3 60- 3 Oct. 1959 \Y 188 Kasiya Police Post no 660 Feb. 16 P.W.D. Weathered Gneiss 300 10-40 1.5 Feb.

1Y ChMt District "\V S )lpira School 14 7 360 Jan. 14 N.A. Kwataine Weatherer! Gnebs 152 10-20 0.7 ]Teb. 1959

Dowa 1Ji,9tricl W 277 Chana . . 103 360 Dec. 55 N.A. Pemba La.ke Sediments 2.8 20- 2.8 I Nay. \V 276 . Garnctt 111 720 Dec. 50 N.A. Karonga Lake Sediments 1.9 20- 1.9 Nov. ,y 278 Chiunda 102 720 Dec. 15 N.A.l\Iaganga Lake Sediments Not Resolvable Noy. W 279 Ndyat.hope 95 720 Dec. 15 N.A.l\faga.nga I,ake Sediment>; 1.3 4()-- 1.3 Nov. ""- 2f)1 Kambwiri 100 720 Dec. 42 N.A. Karonga Lake Sediments 1.7 40- 1.7 i Noy. W 137 Salima TovmshiJl 100 720 Nov. 37 Tmmship Supply - j

P.W.D. Lake Sediments Not Resolvable I Oct.1959 \V 269 Salima II'Iission .. 117 240 Nov. 77 \Vbite Fathers Lake Sediments over Gneiss 28.4 20-100 3.2 Oct.

Rot-a, Kota. D1'sl-rict I ,\y 170' Njakwa 132 150 June 55 S.N.A. Chilooko Sheared Gneiss 36 10-60 4.0 I Dec. 1959 ,:V 172 J)Ialambo . . .. 272 51 July 75 N.A. Chilooko \Veat.hered Gneiss 10 20- 10 1 Dec. 19~9 E 31 ilfwera Hill-Agric. Station 244 205 Oct. 52 Agricultural Department Weathered Gneiss 1.4 40-- 1.4 ]\fay 1907 E 62 Kasanja 93 480 Oct. 78 N.A. Kasakula Weathered Gneiss Not Recorded June 1957 E 61 Chakaka .. 101 400 Oct. 17 N.A. Mwadzama Weathered Gneiss Not Recorded 1 June 1957 E 59 Kalo\viro :M:ission 101 576 Oct. 38 N.A. Mwadzama \Veathered Gneiss Not Recorded June 1957 E 58 l\1taehi.. 102 720 Oct. 16 N.A. Mwadzama Weathered Gneiss Not Recorded I June 1957 E 54 lIIteya.. 109 240 Oct. 40 N.A. Mwadzama Weathered Gneiss Not Recorded June 1967 E 60 I1Iwadza-ma Court 82 720 Nov. 16 N.A. Mwadzama Weathered Gneiss Not Recorded I June 1957

I No. I

W 135 W164 W125 W 126 W 133 W 132

W 129 W131 W130 W 128 W 127

W 88 W 89 W 192 W 87 W 163 W215

t~ W 216 "'" W214

W218 W 219 W 82 W 81 W213 W263 W217 W212

W 161 W162 W189 W236 W238 W159 W220 W260

Z 142 W 158 W 74 Z 144 W77

Z 142A W224 W223 W234 W235

District and Locality

Kasungu District Chiziya .. Kasungu Blind School Gideon Chiwengo .. Simon Kaswancenje Chlsazima

Phembe Chipwaila Chilimbana Malewa Mbambo Chimbiranjara

Northern Province Mzimba Dis~rict

Nchawa.ka Kamando .. Champila Police Post Chimsolo .. Mbawa Agric. Station Swaswa .. Vibangalala .. 1I-Izukuzuku Court Wilson Jere Mzamu .. Yotamu Ng'oma Zabayumo . Njebwa Condwe Chibambo Kandodo Chis! Nelson Nkata

Rumpi District Lukali Chiwaya Mthanila Bowe .. Buwira Monga Kapemba .. Rumpi Leprosarium Site

Karonga District Deep Bay Police Post Mwalughali Lupembe Lupembe Mwenengune

Deep Bay Police Post Mwantawali .. Nyungwe Court Wundaninge Mwaungulu

Depth in ft.

142 101 100 109 121 82

152 171 132

94 81

100 144 152 100 147 170 150 120 171 120 161 120 82

189 140 143

144 140 100 103

83 125 150 257

221 127 164 120 121

60 168 135 145 260

TABLE OF BORED WELLS DRILLE!) N on inue

YIeld G.P.R.

200 288 960 288 411 720

288 60

120 180

60

264 440 264 440

1,320 264 528 440 440 440 220 440 900 900 264 440

900 900 540 900 540 540 900 480

Nil 240 480 900 900

Nil 600 900

1,200 900

Month drilled

Jan. Jan. Jan. Feb. Feb. 1tfarch

March April April Ma.y May

\ March March April April July July Aug. Aug. Sept. Sept. Oct. Oct. Dec. Nov. Nov. Nov.

June July July Aug. Aug. Sept. Sept. Nov.

Jan. Feb. Feb. Feb. June

July July Aug. Aug. Sept.

Rest level (in

feet)

,~

! Sp. Res. ! ' I i lower i Top and Sp. Res.

I layer! bottom wet zone' }.{onth of K.Ohm 11 wet zone K.Ohm I·. survey _____ 1 Cm. , (in feel) Cm.

I I I N.A. Mwase Weathered Gneiss ! No Depth Probe Aug. 1959 N.A. Mwase Weathered Gneiss Not Resolvable I Oct.195g:

Remarks Geology

N.A. Mwase Weathered Gneiss 740 10-80 3.7 I Aug. 1959 55 N.A. Mwase Weathered Gneiss 760 20-80 8.8 i Aug. 1959 55 N.A. MW3se Weathered Gneiss 55.8 10-60 6.2 I Aug. 1959

7 N.A. Mwase-failed June! and deepened by 48 ft. I New yield 288 G.P.R. Weathered Gneiss SOD 20-40 1.5· Aug. 1{J59

80 N.A. Mwaso Weathered Gneiss No Depth Probe Aug. 1959 50 N.A. Mwase Weathered Gneiss No Depth Probe Aug. 1959 50 N.A. Kaluluma Weathered Gneiss Not Resolvable Aug. 1959 41 N.A. Kaluluma Weathered Gneiss 920 20-40 4.6 Aug. 1959

5 N.A. Kaluluma Weathered Gneiss No Depth Probe Aug. 1959

18 8

45 102

N.A. Maulabo Weathered Gneiss I 89 20-40 4.4 June 1959 N.A. Maulabo Weathered Gneiss I" No Depth Probe June 195{) P.W.D. Weathered Gneiss 4.9 40- 4.9 Feb. N.A. Nzikora Weathered Gneiss 26 40-60 2.3 June 1959

19 22 21 33 33 30 30 19 25 41 20 28

Saline-Agric. Dept. Weathered Biotite Gneiss I 4 20- 4.0 Oct. 1959 N.A. Mzukuzuku Weathered Gneiss 8 20- 8.0 Ma.y

1

N.A. Mzukuzuku Weathered Gneiss 5 20- 6.0 May N.A. Mzukuzuku Weathered Gneiss I 55 4(}-100 18.6 May

I N.A. Mbelwa Vteathered Gneiss ! 6.3 i 20- 5.3 June

I N.A. Mbelwa Weathered Gneiss I 46 I 2(}-80 8.1 June N.A. Mbelwa Weathered Gneiss 21 40-80 3.2 June 1956 N.A. Mbelwa Weathered Gneiss I 0.2 40- 0.2 June 1956

. N.A. Mbelwa Weathered Gneiss 4.6) 20- 4.6 May 'I N.A. Mtwalo Weathered Biotite Gneiss I 2,420 1(}-100 12.1 Sept.

N.A. Mbelwa ""Weathered Gneiss 1 Not Resolvable June N.A. Mbelwa Weathered Gneiss ) 6.6 40- 6.6 May

49 N .A. Chikulamayembe 55 N.A. Chikulamayembe 18 N.A. Chikulamayembe 42 N.A. Chikulamayembe 40 N.A. Chikulamayembe 40 N.A. Katumbi 46 N.A. Katumbi

200 Abandoned-Yield insufficient

Abandoned-P.W.D. 69 N .A. Chungu 39 I N .A. Chungu 55 N .A. Chungu 30 ! N .A. Chungu

, Abandoned-P."'~.D. 60 I N.A. Mwafulira 25 " N .A. Mwiringombe 22 I N.A.I\fwafulira

182 ) N.A. Mwafulira

Alluvium over Karroo Alluvium over Karroo Weathered Gneiss Weathered Gneiss Weathered Mica Schist Weathered Gneiss Weathered Gneiss Biotite Gneiss and

Pegmatite

Lake Sediments Lake Sediments Lake Sediments Lake Sediments Cretaceous Sands tones and

gravels Lake Sediments Lake Sediments Lake Sediments Lake SOdiments Lake Sediments

No No

7.8 3.5 3

121 18.5

24.9

No No

1.82 • 1.1 5

No No

2.5 Not I

Depth Depth

20-60 40-10-10--40 20-100

10-60

Depth Depth 40-10-60

40-60-

Depth Depth 20-

Resolvable

Probf3 Probe

2.6 3.5 3.0 0.6 9.2

8.2

Probe Probe

1.82 1.1

1.1 5

Probe Probe

2.5

Ocl.1959 Oct. 1059 Feb. .July July Oct. 1950 June

Sept.

Oct. 1959 .June 1960 Oct. 1959

June 1959 Ocl.1959 JUDe June July July

EVAPORATION AT SELECTED STATIONS 1st November, 1959·31st October, 1960

! I Elevation Draiu -. above

Sanu oJ S{atio'lI age JIJ.S.L. p. Pan

evapora-tion inches

A vt1'age I PeJ'iod inches of 1'ecord

in years

).lakanga (New site) ..

Mimosa

Chisombezi

Naming'omba

Chambe Platean

Bvumbwe .,

Mudi Dam ..

Blantyre

Chileka

Chikv,.'awa

Matope

::\!chcu

Zomba

1Ionkey Ba~y

Chipoka

Salima

Chongoni

]jlongwe

Chitcdze

Nkata Bay

?vIzimba

::vIzuzu

,i(aronga

Deep Bay

area (Approx.)

I.D 175

1.1) 2,000

I.D 3,500

I.D 8,500

I.D ",500 - - .... --_ .... -. .... - ... ------- ..

1.E 3,846

I.E

I.E

I.E

I.L

LP

I.E --- -.. _- ---- ----

2.13 ---_ ... _ .. - -

:3 .. \ . ---_ ... _- ... _ ........

3.1"

·.l.B

4.B

3,500

3,450

2,527

350

] ,f525

4,200

3,140

1",80

1,570

1,675

4,,500

91.62 86.13 7

61.97 70.69 3

72.38 75.40 4

GO.3,' 71.94

56.21 . 1 .- ---... - ... --1-- ... ------ .

02.91 62.14 5

74.30 74.96 5

6l.l3 68.12 9

103.11 106.01 5

79.33 79.97 9

85.94 91.25 6

64.14 64.86 2

60.93 61.90 6

95.49 97.19 8

93.33 93.76 8

76. I 9 82.00 9

03.30 71.48

4.]) :3,1)00 77.09 73.42

:3

9 - ... ---_ ... --- - ........ _-- .. - -----

4.]) 3,GOO 80.27 79.60 (;

(l.G 1,596 69.26

7.A 4,445 80.10 91.99 9

7.1) 4,160 55.65 64.87 9 . - ...... - ... - .. ---.--.... --------..... · ... -------1---1-----·-

8.A 1,575 90. I 7 87.29 8 .......... _ ...

8.e 1,560 97.30 94.89 8

25

Liwondc

Matope

Maganga

Chiromo

SHIRE RIVER FLOW INFORMATION

Mean I Numbe,' I_~:~:'~~HI annual i

l vears Total

flow aC1 e 1'('( 01 d( d flow acr(~

f,:et t _I _ -- _ feet 7",33,899 11 7,204,917

,,----1 . --'--~-

l.ocalion II.C.S. No.

!/B/! 4,490 20,075

17,503,7821 7 ___ ~~292,~~~_ __ __ II!'!~__ 4,580__47:000 I 8)06~36() D 7_,3_S~!2~

I 8,788,482 13 7,234,348 I/G/! ·4,000* 4(i,ii2D

J IP/2 4,880 25,715

The above figures do not take into account the alteration in regime during the period when Liwonde Bund was in position.

"\"Observecl flows from date records started until :Hst October, 1960.

:~Esti11lated reverse flow due to H.iver Ruo backing up River Shire.

November December January .. February IVlarch . April iday June J lIly August September October ..

J10ntli

November December January Februar'y' ?vlarch -April :Mav June July August September October

]V! onth

November December January Februaf)' March . April :VIa)' June July August September October

JI1 on tit

Monthly Flows at Selected Stations SOUTHERN PROVINCE

l{uo AT SANKULANI RG.S. l1DI" Flow (Cusecs)

1959···60 Average ... ---.---~ ----- .. --- Over

11,11 aximmn 111 ini1nuwt M eam. 7 Years

4,91;, 8.200

35,000 20,000 18,000 12,000

1,800 3,400 7,300 1,450 5,250 1,2t)0

260 220 487 ,167

1,390 817 680 600 ,,34 :300 282 17H

S"I 928

2,045 2,924 4,321 2,122 1,005

807 1 ,585

540 712 284

763 2,061 4,112 4,988 3,907 3,80S 1,344 1,062

824 GOr; 431 298

CENTRAL PROVINCE LILONGWE AT LILONGYVE TOWN H.G.S. 4/Dj..J.

Flow (Cllsecs)

1959··60 Average

jl~~X~"u~~ !11~,cn101~1~~I;an ..2~';;~. 0.8 0.3 0.6 10

1.06.1 0.3 118 137 1,OO() 15 179 275

712 44 263 987 491 91 194 662 lIS :J7 69 354 38 II 20 149 14 10 II 65 1J 7.0 8.8 41

S.8 1.9 5.4 27 3.8 2 ') 2.8 15 2.1 0.5 1.3 6

NORTHERN PROVINCE SOUTH H.l;KURU AT P\VEZI H .. G.S. 7jUjl4

Flow (C1£SCCS)

1959-60

ivIaximU11Z l11inimum AI ean

135 57 93 1,319 104 350 2,080 394 1,109 2,289 1,25f5 1,837 3, I 90 2,]] {5 2,651 :~,555 1,567 2,44f1 1,649 760 96:,

75;5 528 646 521 370 440 369 260 3](i 258 180 220 17H 123 150

27

Ave1'age Ove1'

3 yea1's

80 304 H42

1,524 2,451 1,872

694 ,154 :J21 237 102 III

River Location

RIVER FLOW INFORMATION

1st November, 1959-31st October, 1960

i I

Catch-ment area

, sq. miles

Total Flow 1959/60 acre feet

) IRun ofjper sq. mile I No. oj days oJ ! IMea.n Annuall a(J1'ejeet No. of I No Flow

Flow i : Years i i Min. Flow Mao;. Flew cw>eIJs*

----~-----:.----------.-------SOUTHERN PROVINCE

Lirangwe

i R.G.S. I No.

111011

, 11E/l i 11EIZ

acre feet I I Mean Rec07ded! !I Mean cusecs* , ___________ ! i 1959/60 ! Annual 11959/60, Annual. ___ _ '-! ' i'----i·-------

Mwamphanzi .. Likabula. (Lower) Naperi .. Mudi .. Maperera Tangadzi East Ma.senjere " Tangadzi West __ Mwanza (Lower) " Mwanza (Upper) Wamkurumadzi

~ Ltsung\ve r;;r:J R,ivi-Rivi

R,uo Ruo Ruo Tuchila Lichenya Nswadzi Nswadzi Nswadzi Luchenza Luchenza Kwakwasi Sombani Ylunguzi Mlunguzi Weir Mlunguzi Weir Palombe Likangala Namadzi Dom&si

}\{atope Road N sanje Village Chikwawa ., Chikwawa Road Mudi (above dam) Mafume Village Ng'onge Village .. Chiromo/Chik-wa,ya Road Nyamalambo Tomali Village . . . . :r-.:Iwanza P.E.A. Border Road .. U IS Chileka/M wanza Road l\Ioffat Village .. IUvi·Rivi Govt. l~arm Sankulani :r-.llanje Ruo Estate .. Chionde Mlanje Chipunge .. :&-Iagombe .. NYasa Tea Estate Plywood Factory .. Llmbe/Nansadi Road BlantyrejCholo Road Paloni Hill Zomba .. Zomba Plateau Zomba Plateau Rigola Village Limbe/Zomba Road LimbejZomba Road Zomba/Liwonde Road

1

11EI4 11EI10 11Fl1 11FI2

1 I1FI3 , I1GI4 ; 11Kll

I, l1KI3

11MI2 ! 11011

111RI3

I IIDI5 I1DIO I1DI22 IIDI3 IIDI10 11DI12 1IDI17 1IDI16 1IDI23 11DI2D 11DI24 21AI2 21BI2 2IBIS 21Bl11

, 21B/4 I 21B15 1 2IBI6 I 210/1

78 117 218

8 3

25 19 8

152 630 35

205 461 300

1,869 78

213 540

28 147

37 22

198 102 26

289 10

7 3

537 26 11 30

4,556 21,251

9,812 1,220

270 4,590 7,846 3,187 1,742 3,475 9,665

71,835 112,080

55,907 1.091,885

309,687 574.354 120,705 202,584

67,621 21,166

6.639 58,555 17.682 10.341

556 10,284

8,445 4,092

122,636 13,985

2,075 24,702

30,606 56,330 53,886

5,476 1,596

15,457 13,916 3,843 9,714

83,859 29,939

128,771 173,335

90,713 , 1,445,953 !

377,214 577,387 195,534 139,119 121,206

37,745

58 182

45 153

93 184 413 398

11 6

276 350 243 186 584

5,124 2,696

224 7,235

460 572 302 296 173 398

15.973 118,953

52,889 15,624 48.543 17,592 13,667

5,725 380,407

26,292 6,423

44,961

2 I 1,028

1,206 1,516

228 538 189 823

392 481 247 685 548 618 732 480

64 133 855 628 376 302 774

4,836 2,711

362 4,969

824 I 1,020 , 726

601 519 601 168

1,759 1,953 2,120

708 1,011

5S4 1,499

9 8 8 7 5 8 7 7 6 8 6 7 9 7 7 7 5 8 7 7 6 6 (\ 6 8 8 8 5 4

11 8 8 8

I 191 ! ~il 83

Nil Nil Nil Nil Nil 354 287 Nil Nil Xit 25

Nil :Nil Nil Nil Nil Nil XiI Nil Nil Nil :r-ril 144 Nil Nil Nil 92

Nil Nil Nil

*' Minimum and Maximum flows shown are the lowest and highest recorded flows since records commenced. E-Estima.ted.

41 Xil

24 :Sil Nil Nil Nil Nil 262 143 :Nil Nil :Nil

14 Nil Nil Xii

1 Nil Nil Nil Nil Nil

2 Nil 65

Nil :Nil :Xil

46 Nil NU Xli

Nil 0.3 Nil

0.05 0.005 0.60 2.70 0.20 Nil NU

1.5 15.0

4.5 Nil

65 7.5

25.0 Nil 3.0

17.0 5.0 2.7 Nil Nil

0.41 Nil 0.10 2.52 1.1 Nil

0.80 0.30 0.50

7,600E 4,190 6,600 4,800

141 4,000

13,750 700

3,240 4,700 1.415

13,700 20,400 9,000

190,000 30,000E 33,DOOE 25,000 14.000E 15,250E

3,000R 2,517 8,000 5,200 3.700 2.600

400 346 230E

11,360 2,900E 2,500 4,000

River

OENTRAL PROYINOE Nadzipokwe . _ Namikokwe (Lower) Nadzipulu Linthipe Lilongwe Ltngadzl Bua :Sua

NORTHERN PROVINOE t-.:;l Limpasa t.O Luweya

S. Rukuru S. Rukuru Lunyangwa Lunyangwa Kasitu Kasitu RunYina Luviri .. N. Rumpi Lura .. Kaziwiziwi Kambwia N. Rukuru Wovwe .. Chittmba Nyungwe Songwe

Location

Ktakataka (}lua Mission) Escarpment Road to Dedza Near Ntakataka Salima ._ Lilongwe Town _ . Lilongwe/Salima Road Bua Bridge.. .. Lilongwe/Ft. Manning Road

Limpasa Dambo Luweya Ferry Road Pwezi Henga Valley Ohimsewezo Ekwendeni l\fzuzu Causeway Njakwa Edundu .. .. RumpijChisenga Road Ng'onga .. .. NjakwajLivingstonia Road Lura .. .. NjakwajLivingstonia Road Near Nohenachena .. Mwankenja.. .. KarongajDeep Bay Road Karonga/Deep Bay Road Nyungwe .. .. Mwangulukulu V11lage

RIVER FLOW lNFORMATION-(Continued)

1st November, 1959-31st October, 1960

R.G.S. No.

3/E/1 I 3!Ei2 I 31Pl3

41Bll 4/D14 4fE/1 51DI2 5/E/2

61F/I 61~'12 71GII< 71AI3 71DI3 71DI5 71DI7 71DN 711'11

'I 71GI13 71GI2

I 71GI8 I 71GI15 ! 71Glll

I, 81AI2 81Cl2

I, 81013

81014 , 9/Bl1 I

[Run off per eq. mile I I No. of days of [ Oatch- Total Flow lvlean Annuali acre-feet No. of! No Flaw 1

men,t area 1959/60 Flow! I Years , I Min.Flow I Maz.FlcwJ sq. miles acre/eet acre feet I, 1 Mean Reoordedl', I Mean 1 C'U8ec8* cusecs* i 1959/60 Annual 1959/60 Annual ----------- 1 1---

70 54 86

3,266 730 321

2,722 137

106 900

40,577 362 190

10 S04 283 346

20 117

'7 61 43

753 134

11 155

1,567

8,785 34,537 58,468

461,433 52,400 32,217 i

129,063 I 8,447

100,065 671,105 675,020

42,586 71,560 18,116

125,474 i 2g6:~~gE !

13,396 213,525

18,682 88,366 56,719

443,035 78,344 16,302

109,778 1,118,658

13,020

46,954 779,777 161,215

60.787 420,213

30,380

88,704 701678 548:534 47,607 69,172 13,796 99,127 66,512

164,336 9,601

152,904 13,953 62,437 44,018

288,829 61,003 86,819

109,204 920,159

126 640 680 141 72

100 47 62

044 746 147 118

, 377 I 1,812

156 113 581 670

1,825 2,669 , 1,449 ! 1,319 i

588 . 585

1,482 708 714

186

546 239 221 189 154 222

837 780 120 132 364

1,380 123 235 475 480

1,307 1,993 1,024 1,024

384 455

7.893 705 587

6 1 3 7 7 7 6 6

7 7 3 4 6 7 4 5 6 2 7 6 7 7 7 7 4 4 7

i Nil Nil! '[ Nit Nit'

Nil Nil ! 37 28 I Nil 3 I Nil NU '83 35

41 15

Nil Nil Nil 55

Nil Nil 24 87

Nil Nil Nil Nil Nil Nil Nil Nil Nil no Nil

Nil Nil Nil 30

:Nil Nil 34 49

Nil Nil Nil Nil Nil Nil Nil Nil Nil 116 Nil

0.20 .3

3.10 Nil Nil 0.1

Nil Nil

6.5 120

66 Nil 0.6 1.0 Nil Nil

20.0 1.8

46.0 3.0

23 11.5

7.0 8.0 1.3

NU 102

2,700 l,800E 4,000

34,250E 8,650 6,000E 4,688 1,500E

3,172 13,000

3,600 l,200E 6,000E

190 2,600:&

13,000 1,600

250E 3,000

250E 1,300

465 14,000E

I,OooE 1,000:&

14,000E 7,700

(I. Minimum and Maximum flows shown are the lowest and the highest recorded flows since records commenced. E-Estimated..

SUMMARY OF SILT FACTORSt

Sill i19;)[J60 Estim,ated colluhng ]v! ea.n Number maximu.m, H.G.S. HilJ1'r area FactoI' a.nnual of years daily load No. sq. 1'1'Z/:tCS tons*'

.---.---.---~ ----_ .•. - .- --_ .. _-------- .. --.---- .. _-.- _._._---.---I/C/I Lirangwe 78 1.81 2.01 9 50,000 I/D/24 , Kwakwasi 2(\ 0.65 0.62 8 8,000 I/D/3 Tuchila 540 1.42 1.36 9 GO,OOO I/D/5 B .. uo' 1,869 0.48 0.51 7 900,000 I/D/9 Ruo 78 0.11 0.07 7 18,000 I/D/I0 Lichenya 28 0.09 0.06 7 2,600 I/D/12 Nsv,radzi 147 0.24 0.41 6 18,000 I/D/16 Nswadzi 22 0.18 0.55 6 8,000 I/D/17 Nswadzi 37 0.68 0.76 6 18,000 I/D/20 Luchenza 102 0.49 0.80 6 17,000 I/D/22 Euo 21 :3 0.18 0.13 6 33,000 I/D/23 Luchcnza 198 1.62 I. 70 6 ,58,000 I/E/I M \v~m phanzi 117 0.58 0.72 8 30,000 I/E/2 Likabula 218 0.46 0,57 8 20,000 I/E/3 Mudi 7 0.84 0.93 8 3,200 I/E/4 Naperi 8 0.58 1.35 7 10,000 1/1'/1 Mapercra 25 0.45 0.5G 8 8,000 I/F/2 Tangadzi East 19 0.87 2.05 7 30,000 I/F/3 Mascnjere 8 0.36 0.54 7 4,000 I/G/,[ Tangadzi \Vest J52 U8 1.31 6 9;000 I/K/3 MwaI).za 35 0.10 0.27 6 4,800 I/K/I 1\1wanz3 GaO 0.02 0.10 8 5,000 I/M/2 '\Vankurumadl.i 205 0.Q7 0.12 7 3,000 1/0/1 Lisungwe 461 0.30 0.42 9 32,000 I/E/3 Ri.vi-;Rivi 300 0.96 1.07 8 70,000

2/A/2 Somba-nj 289 0.02 0.02 9 250 2/B/2 :rvllunguzi 10 0.10 0.07 9 600

2/B/4 Palombe ;)37 1.32 1.04 9 HO,OOO 2/B/5

, Likangala 26 0.25 0.24 9 4,000

2/B/6 Nainadzi 11 0.22 0.40 9 8,000 2/B/IO Palombe 26 0.24 0.17 5 1,000 2/C/I Domasi 30 0.04 0.08 9 2,000 3/E/I Nudzipokwc 70 0.48 0.65 :1 9,000

:3/E/2 N a,mikolnve 54 0.27 I 1,800

3/1'./3 Livulezi 1.0 I 1 7,000

*NIaxim.lIm figure since records commenced

Total Annual Silt Load in tons 'j"Silt factor~~ .-''''

Total Annual Flow in Acre Feet

30

I II.G.S.

iVO. ,-_._------ - -- - .

:JfF/2 3/1'/3 4/Bfl 4/D/4 4/E/l 51D/2 5/D/3 "/E/1 5/E/2 6/F/l 6/F/2 7/A/3 7/D/3 7/D/4 7/D/5 7/D/7 7/F/I 7/G/2 7/G/3 7/G/8 7/G/Il 7/G/13 7/G/14 7/G/I," 8/A/2 8/C/2 S/C/3 9/B/l

SUMMARY OF SILT FACTORSj",,(CoJltinued)

! Sill I collecting 19,'9···UO

I( it'lT «,rea Fa.ctor sq. m£les I

. . .... - ... _ .. _.,.,-- . -_.-.- '-"--' Nakaing\\'a · . 25 0.09 Naclzipulll · . 86 0.51 Linthipc · . :3,266 0.41 Lilongwc · . 730 0.18 Lingaclzi · . · . 321 0.06 Bua .. · . · .

I 2,722 0.01

Mtiti . . · . 89 0.17 Namitete · . 65 0.06 Bna · . · . 137 0.04 Limpasa 106 0.19 Luweva 900 O.ll South'Rukufll · . · . :362 0.13 r~unyang'\'a · . 190 1.20 Kasitu 288 2.23 Lunyangwa · . · . 10 0.08 Kasit.u 804 1.56 Runyina :346 0.14 North Rllmpi 117 0.16 Muhllj\l · . 2f1 0.31 Lura · . 7 0.10 Kamlnvia · . 4:1 O.On Luviri 20 0.24 South .RukuJ'u , 4,;177 0.44 Ka7.iwiziwi.

I

61 O. I 2 North Hukllru 75a 1.37 · .

I \\lov\\'(' . · . · . 134 0.24 Chitimba · . 11 0.49 Songwe 1,;167 I 0.29

I

*Ma::-jmnm figure since records commenced.

Total Annual Silt Load in tons i-Silt Factor= -~-.- -----.--.-.-.-

Tota! :\nnual Flow in Acre Feet

, I I

I I , I

.Mf'an Nun~ber annual of yea.rs

... . ,--,-- .. '-,-_._-

O.ll .2 0.49 :3 0.68 6 0.15 7 0.12 6 0.04 6 0.24 :1 O.ll

"' 0.10 {j 0.17 0 0.15 0 0.12 4 1.43 0 2.12 5 0.09 f') 1.86 4 0.18 !i O.ll (; n.24 ;; 0.06 r; 0.04 ;, 0.23 :1 0.40 2 0.08 :1 1.23 ti 0.22 Ii 0.45 ~ 0.23 Ii

I Estimated 1naximum daily load

tons* _._" .. _---_.-.-

200 6,000

400,000 4,500 8,000 1,090 1,000 3,000 1,800 8,000

50,000 1,000

18,000 62,000

100 60,000

2,800 2,300

700 290 260 280

8,600 1,000

90,000 5,000 4,000

12,000

: ,

; i I

rnt1l-l-

I i __ It t-IT r-I~~

._-

--

I, I 1- t--r I-+++t-t-H+-t-----r-_~_~,. rTT1i+ r_l~~-

. .J--'... ~ +J·t ~ -~t IL-+ ~-- 4tt ,t t-~1 __ _ ~I- ~j~ tt li r-, -t-

, , , --I-

n

~ f- -1-· ~

-~T~ ,

.~ -J:-

~ I- r-~

.j-

. --

-j-

+ .+H-t-rH

-g 8 ~me1l 9 ___ .~L ___ ..J_~ __ _____' ___ , ___ ..L.._. ___ _'_ ___ _

~. ~ 11 0

0 0 -~~"'" ,,-

I11

. J - 1

'~ ~ O~ ~

1 f..!! "J. 4t WI

- 1~ : Q

~1it .): iD..

!~ ~

!J1:.

-j~ :l -I;:i ~ .... :1

f++I+

'", Q

id? r _Ij :lI:

-l:b Z 1§ .at

I+U

lli± 1

ttlli ill

l~ ...I

ill

If ':Jl £. z

l~ «t -~ I-

11~

tl w

u:u m :>

1~ rJ Q ~

11,1 ott. 1 10 ~ c -

~I ~ 1>- ~

~ 0 l~ ~

-'

-i~ .. ~ .. ,,· .,"

~

0 r-" 0 8 0 -~ ;)um 0 ~ -0 Q

I~ , - -I- & - u

-. Ib 0 ~ -:)::1:::.. ... -.--

i- si. .... ._._-

.-c.. t -t- !AI 4( ++ 'If> IiA HI-- . ---4 --- .e:::.

)0-

~ J. ::;) 0 -i-~ +----

r--- . .;t

- ... - ; ~ ~ \!»

..l Q 'J -0.. tL .. Cl. ~ , _. .- -:s:: ~ 4( .~.±= ~ "'" .c , , :?: ,-j--~ !' -z J.

,.--_.

-«: 4t ... , ::» ~

I::::::--:c ...., NI

--r ... . - -- --_. _. . -Cl Q ~ - , ~ ...-j-- - >-~ 0 Z

0 ~

~'U ", g 0 0 0 Q

Q q ~-

o o

HVD

• o •

."

l ....

LtenD

0-""»1'" JTlTlOU

'''UClf IIC""T "",,,*'.10. SflllOfff