Surface and Ground-waterModelling Using

Remote Sensing and GIS Methods

ARJUN GANGADHARAN

RVS Faculty of EngineeringCoimbatore

3rd year Civil Engineeringarkarjun@gmail.com

The Art or Technique or Science of obtaining reliable information about the physical objects and the environment through the process of recording,

measuring and interpreting imagery and the digital representation of energy pattern derived from non

contact sensor system

Remote Sensing

Requirements for Remote SensingSourceObject SatelliteGround station

As you view an object, you are actively engaged in remote sensing. A physical quantity (light) emanates from the object, which is a source of radiation. The radiated light passes over a distance, and thus is "remote" to some extent, until it encounters and is captured by a sensor (your eyes). Each eye sends a signal to a processor (your brain) which records the data and interprets this into information.

Remote Sensing in Daily life

ObjectivesProper management of surface and ground water resources is an important step against water scarcity.

Runoff estimation based on rainfall is the first step in water management.

Based on United States Department of Agriculture (USDA) Soil Conservation Service (SCS) Method the runoff calculation is done.

The Survey of India (SOI) Topographic maps for the demarcation of the watershed line.

The rainfall data from Meteorological Department.The land use and land cover map prepared from satellite imagery.The drainage map prepared from SOI Topographic

sheetThe soil information was collected from the Soil Survey of India

Data Required

1. Land cover/land use classification2. Trend analysis3. Ground water flow system study 4. Rainfall – runoff modelling methods5. Rainfall runoff-soil conservation

system-curve number method6. Hydrogeological evaluation and mapping7. Hard rock terrain and lineaments

analysis8. Thermal imagery study9. Soil types analysis

Steps involved

Land Cover Map

Rainfall Map

Drainage Map

Thermal Map

Soil Map

SCS-CN theory is based on the fact that direct runoff depends on land cover, land use, soil type and antecedent moisture conditions of surface soil. Several accompanying tables had been developed in association with empirical equations

Applying SCS method on a large area, with variant specifications, would be almost impossible if done manually. Regarding this matter, an automated computer model is needed to achieve desired accuracy.

CONSERVATION SYSTEM-CURVE NUMBER METHOD

SCS rainfall runoff model, developed by United States Department of Agriculture (USDA) provides an empirical relationship estimating initial abstraction and runoff as a function of soil type and landuse.

Q = P – (Ia+ F)

Equations and Relations1.The water balance equation is expressed by

2.Estimation of rainfall runoff using SCS-CN model is defined by

3.For Indian soil condition the above relation is modified as

4.The SCS rainfall runoff model is modified to include parameter – watershed area, slope, drainage length, and land cover. The equation for average runoff Qa is defined by

and

Curve Number Map

The Curve Number (CN) is an index developed by the Natural Resource Conservation Service (NRCS), to represent the potential for storm water runoff within a drainage area.

ConclusionThe data and analysis reports can be used in modelling. It gives a clear picture of the nature of runoff in the study area. The study report can be made use for the feasibility studies for the

construction on reservoirs or dams. The method can be employed in the efficiency study of the

catchment. With results we can estimate the total volume of runoff volume the

area, which is employed in many other studies such as predicting the flood areas during monsoon. The water scarcity of the area can be minimized by the

construction of rain water sheds/tanks.The suitable locations for dams and reservoirs can be obtained in

such a way that the maximum runoff volume is collected by it.Remote sensing and GIS techniques allow such analysis to

performed in a short time, at high accuracy and low costs.

Queries ??? Thank You !