A GIS-based Modeling For Groundwater

Vulnerability Index in Tuul River Basin,

North Central Mongolia

V.Ulziisaikhan, M-Eng., PhD Student, MUSTEmail: terelj@gmail.com

N.Jadambaa, PhD - HydrogeologyEmail: jadambaa_n@yahoo.com

D.Batjargal, BSc. – HydrogeologyEmail: bachka_8@yahoo.com

Ulaanbaatar, 2010

A GIS-based Groundwater Vulnerability Index in Tuul River

Basin, Mongolia

Geography:

•Elevation: 742 ~ 2780 m

•Area: 49,744 sq. km

•River length: over 700 km

•Upstream: From Terelj, Khentii Mountain

•Downstream: To Orkhon river

Climate:

•Mean annual temperature 0.2 ~ -4.3 C

•Precipitation ranges 240 ~ 392 mm

•Annual potential evaporation - mm

Study Area: Tuul River Basin, Mongolia

Groundwater Exploitable Resource Map -Tuul River Basin

METHODLOGY

DRASTIC - US Environmental Protection Agency (Aller et al. 1987)

Factor , (1-10) Description Weight

D Depth to Water From ground surface to water table 5

R Recharge Amount of water which penetrates to GW. 4

A Aquifer Media Saturated zone properties 5

S Soil Texture Weathered portion of unsaturated zone 2

T Topography Slope of land surface 1

I Impact of VadosZone

Unsaturated zone properties 5

C Conductivity Ability of aquifer to transmit water 3

DRASTIC Index = Dx5 + Rx4 + Ax5 + Sx2 + Tx1 + Ix5 + Cx3

Parameter Map – Depth to Water

Parameter Map - Recharge

Parameter Map – Aquifer Media

Parameter Map- Soil Texture

Parameter Map- Topography

Parameter Map- Vados Zone (I)

Parameter Map- Conductivity

RESULT – ҮР ДҮН