Site Selection of Rain Water Harvesting Structures Using Remote Sensing and GIS Techniques for Diluting Fluoride Concentration in Groundwater

Water is a natural resource, basic ingredient of life, agriculture, industry and economic development of the country. Groundwater constitutes major source of drinking water and more in rural areas of our country. India is facing the major problem of drinking water due to quality mainly in the rural areas. Quality is major when compared to the quantity of water. Thus, provision of safe drinking water to the entire rural population assumes a primary and essential task. Among the groundwater quality parameters fluoride is the main constituent which affect the quality of groundwater which originates in subsurface aquifers in different rock types. Fluorite and apatite are the principal bearers of fluoride and are found in granite and granite gneiss. Fluoride had both advantages and disadvantages on the human body depending upon the limit of intake. Below the permissible limit is safe it is 1.5mg/l. Beyond this limit it causes dental and skeletal fluorosis. Dental fluorosis means the enamel part over the teeth get effected and depending on the intensity we can observe white patches on the teeth in starting stage then yellowish color marks appeared on the teeth then finally the teeth contains brown patches. Skeletal fluorosis means the bones get deformed and unable to walk properly. The present study aimed to identify the fluoride effected zones and areas to construct rain water harvesting structures like check dams, desilting of tank, percolation tanks, nala bands, recharge pit etc. for diluting the fluoride concentration in groundwater of Narketpally mandal, Nalgonda district, Telangana State, India. Fluoride analysis both from the surface and groundwater sources like open wells, bore wells, dug wells etc. was carried out to estimate fluoride levels and correlated with geology, geomorphology to identify the low and high fluoride groundwater zones. Various thematic maps such as Geology, Geomorphology, Soil, Slope, Land use and Land cover etc. were prepared using remote sensing data of high resolution. These layers along with geology, drainage and slope were integrated using GIS techniques to derive suitable water harvesting sites. The rain water harvesting structures are constructed on the upstream of the drinking water thus infiltration takes place more and also stores water these waters can be used for the agricultural purpose and also for other purposes depending up on the usage. These rain water harvesting structures not only dilute the fluoride level in groundwater but also increase the groundwater level. As the groundwater level increases the area under irrigation also increases.