CS(AR)-202 : Assessment of waterlogging in Shriram sagar command area

Abstract

Waterlogging is becoming a serious problem in command areas and although the area affected by waterlogging has been small, it is spreading slowly. Shriram sagar command area has been selected for this study, which is about 120 km north of Hyderabad. This area was chosen because, after the construction of the main canal and subsequent release of water from the canal system, it was observed that in certain regions the groundwater table has risen rapidly.

The groundwater rise in Shriram Sagar command area was also partly due to non-usage of groundwater compared to canal water. This has resulted in making the water of the crops leading to a drastic reduction in their yield. The historical rise in groundwater level is 4.43 to 5. 86 m over a period of 10 years. In this study an attempt has been made to make an quantitative assessment of waterlogged area and sensitive areas to waterlogging during pre & post monsoon period in the Shriram Sagar command using remotely sensed and field data.

A rapid and accurate assessment of the extant of waterlogged areas can be made from using remotely sensed data. Visual interpretation of IRS-1A-LISS-II FCC of April 12, May 27, October 6, and November 18, 1989, (path 25, 26 row 55) was carried out to prepare land use, drainage map and delineation of waterlogged area in the Shriram Sagar command area. IRS-1A-LISS-II digital data ( CCTs) of April, and October 1989 were analysed to assess the areas affected by waterlogging and the areas sensitive to waterlogging. An attempt has been made to validate the IRS derived waterlogged area with the available water table depth data and other field informations.

The result obtained from this study indicate that in April and October, 1989, an area of 388 and 540 sq.km was affected by waterlogging and about 698, 802 sq.km area was sensitive to waterlogging, where water table lies in between 0 to 3 m respectively. It is suggested that periodic assessment of waterlogging using remotely sensed data should be carried out in the Shriram Sager command.

The annual rise in groundwater level is 2.0 m to 4.8 m, them rate of rise varies between 0. 17 to 1 .2 metres per month and the rate of fall varied between 0. 25 to 0.84 metres per month.

The IRS data have been proved to be very successful for the assessment of waterlogging. Density slicing and principal component analysis are useful techniques to make an assessment of waterlogged areas in irrigated command area.