Abstract:
Measurements of water levels in open wells form the most important part of groundwater investigations. Water level data is analysed for monitoring changes in the storage of groundwater in response to rainfall, pumpage, surface irrigation etc., The data is also essential for forecasting future trends of water levels. Water table contour maps are useful in identifying recharge and discharge areas and to find out the direction of movement of groundwater.
Records of water level fluctuations are being obtained in about 1650 observation wells in the Andhra Pradesh. Apart from these the State Ground Water Department has established a network of about 1000 observation wells spread over 12.47 lakh ha. of irrigated area under the four Major Irrigation Projects. Manual measurements at regular intervals ranging from one per week to one per month are made with a tape. Water samples are being collected from all these wells twice in a year and analysed for chemical constituents.
The frequency of the measurement depends on the nature of fluctuations and on the intended use of the data. The various factors that govern the selection of network density are discussed. Statistical techniques for selecting the optimum number of observation wells are indicated. The criteria adopted for selecting observations wells are outlined. The objectives of collecting the data are summarised in this
report.
