ABOUT RAIN water and Ground Water
Hyderabad has a tropical wet and dry climate bordering on a hot semi-arid climate. The annual mean temperature is 26.6 °C (79.9 °F); monthly mean temperatures are 21–33 °C (70–91 °F).Summers (March–June) are hot and humid, with average highs in the mid-to-high 30°s Celsius;maximum temperatures often exceed 40 °C (104 °F) between April and June.The coolest temperatures occur in December and January, when the lowest temperature occasionally dips to 10 °C (50 °F).May is the hottest month, when daily temperatures range from 26 to 39 °C (79–102 °F); December, the coldest, has temperatures varying from 14.5 to 28 °C (57–82 °F). The highest temperature ever recorded was 45.5 °C (114 °F) on 2 June 1966, and the lowest was 6.1 °C (43 °F) on 8 January 1946. The temperatures reaches 45º C during the summer season and with the onset of monsoons during June the temperature drop and varies between 26º C to 38ºC.
Heavy rain from the south-west summer monsoon falls between June and September,supplying Hyderabad with most of its mean annual rainfall. Since records began in November 1891, the heaviest rainfall recorded in a 24-hour period was 241.5 mm (10 in) on 24 August 2000. The average annual rainfall is 790 mm. The south west monsoon contributes 74% of annual rainfall and north east monsoon contributes 14%.
The city receives 2,731 hours of sunshine per year and 100 hours of rain fall per year; maximum daily sunlight exposure occurs in February.
||Deficit/Surplus( w.r.t to avg. Rainfall)
Groundwater occurs under phreatic conditions in weathered zone and under semi-confined to confined conditions in the fractured zones. Ground water was exploited through shallow, large diameter dug wells until 1970 to meet domestic and irrigation requirements. Presently ground water is being exploited through shallow and deep bore wells with depth ranging from 60 to 600 m.
More than 97% of the area is underlain by the Archaean group of rocks consisting of mostly pink and grey granites and the remaining 3% of the area is underlain by the Alluvium. Accordingly two aquifer systems exist in the area, i.e. Aquifers of the granites and Aquifers of Alluvium.
Groundwater Levels and Analysis with Hydrograph
The depth to water levels in general varies between 5 and 20 m and average water level is 12 m. The depth to water level during pre-monsoon period varies from 2 m to 23 m bgl and that of during post monsoon period varies from 1.5 m to 20 m bgl. The population density and associated ground water draft guide the occurrence of water levels at deeper depths. In general, the depth to water level declines upto 20mbgl during pre and post monsoon periods based on formation (Shallow basement) and demand on groundwater draft in the areas like Maredpally and Sanath Nagar). The depth to water levels are shallow in adjacent to the surface water body (Lower tank bund).
The high draft in dense urban agglomerations has resulted in drying up of shallow hand pumps (Miyapur, Kukatpalli, Chanda Nagar, Dilsukhnagar, Sanath Nagar, Madhapur and Maredpally etc).
composite hyderography of hyderabad
Reduction in Recharge
During the last 4 decades there was an increase of residential area (10-44 %) and reduction of vacant land (38 to 2 %) and open spaces, parks and play grounds together account 6.81% only. The area under transport and communication also increased from 6.67% to 10.87 %. The drastic changes in land use pattern resulted in altercations in hydrological cycle and had greatly reduced the scope of natural recharge to ground water body. Water conservation is practiced in very few buildings.
Conclusion& Recommendations forfurther Groundwater Development:
25-30 % of total water requirement is being met through ground water in Urban areas. Considering the limited potential of hard rock aquifers, reduced recharge and the resource is being tapped from deeper depths, any large scale development of ground water resources is not advisable without adopting proper augmentation practices and strict implementation strategies.
In view of huge availability of larger roof areas, adoption of various water conservation measures is the need of hour. Delay in implementation of various conservation methods large scale will lead to a further depletion and contamination of ground water.
Hence, the Roof Top / Rain Water Harvesting is required to implement on mandatory basis in urban areas.