Rain Water Does Not Drain from Hills to the Streams, Even after Heavy Rainfall [50 cms]

Rain Water Does Not Drain from Hills to the Streams, Even after Heavy Rainfall [50 cms]

We have a situation in the part of western ghats, Coimbatore, where a specific region of hill ranges, water drain is NILL from the hill to the respective stream paths. We can approximate the average rainfall on the specific hill catchment area is about 50 - 100 cms in a period of 2 months. Have visually ensured, no deforestation or no developments of civil constructions. We, the public, realized the gradual decrease in water flow to the stream from past 10 years, but the heavy monsoon shower helps to revive the water beds by getting the life of those streams back to normal. But past couple of years despite normal rainfall, no water drained from the mountain range. The stretch of mountain range impacted by this change is about 10 miles, which is about coverage of 2000 hectares of agricultural land. I seek technical assistance and help to understand the cause of the absence of water drainage and revive the situation. CO_ORDINATES :  10°55'13.43"N  76°47'32.54"E   Thanks Murthi