11-A case study on infiltration modeling in upper Bhopal Lake catchment

Abstract

The management policy for any lake depends upon the inflow of water and nutrients into the lake from its catchment. The catchment characteristics such as geomorphology, geology, hydrological soil properties influence to a great extent the magnitude of inflow into the lake. Infiltration and soil-water movement are perhaps the most important hydrological processes, since they determine the rates and amounts of water reaching the lake. For a judicious and optimal planning of water and land resources, the soilwater infiltration studies are imperative and inspite of this fact, modeling of infiltration is the area in which sufficient scope for research work exists. An attempt has been made to model the infiltration and conductivity in the catchment of the upper Bhopal lake. Double ring infiltrometer tests and field saturated hydraulic conductivity tests using Guelph permeameter have been conducted at twelve sites within the catchment area of 361 sq. km. of the upper Bhopal lake. The Horton's infiltration model has been fitted to the experimental data and the value of parameter (k) varies between 0.69 and 4.96. Similarly, Kostiakov's model has also been fitted to the experimental data for the evaluation of the cumulative infiltration depth. The infiltration capacity of the soils lying within the catchment of the upper Bhopal lake varies between 0.80 to 4.20 cm/hr. A regional infiltration model has been developed considering the experimental data of eight sites and the regional value of Horton's coefficient (k) is estimated as 1.22. The model is validated on the experimental data of the remaining four sites and the correlation coefficient during calibration varied between 0.66 and 0.96 whereas the correlation coefficient during validation varied between 0.77 and 0.96. The results of the Guelph permeameter tests indicate that the field saturated hydraulic conductivity in the catchment area varies between 0.02 to 3.34 cm/hr.