Mangrove Forest Restoration in Andhra Pradesh, India - Global ...

M. S. Swaminathan Research Foundation3.2. Hydrological and geomorphological causesReduction in fresh water flowThe Krishna river is one of the highly utilized rivers in peninsularIndia, for a variety of purposes. As a result, there has been a reductionin fresh water flow over a period of time, which has had a tellingimpact on the growth and regeneration of mangroves.Decrease in sediment load into the mangrovesThe decrease of sediment load has also had an impact on the ecosystemby way of reduction in sediment supply, due to which the nutrients whichare needed for the health of the mangroves have also been reduced.Cyclones and storm surgesThe Krishna mangroves have borne the brunt of two severecyclonic storms in 1977 and 1990. Though the destruction ofmangroves due to these cyclonic storms have not been properlydocumented, the surges associated with these storms have causedextensive sand casting resulting in the area becoming unsuitable forgrowth and survival of many mangrove species. It has also resultedin the siltation of many drainage channels that were feeding bothfresh and tidal water, as a result of which the mangroves havebecome degraded.Geomorphological changesThe sand spit in the Kakinada Bay has undergone changes in itsmorphology with a rapid rate of growth. The spit which had justshown up in the year 1851 has now extended to about 18 km inlength. In addition to this, the Kakinada Bay has been undergoingrapid siltation, as evidenced by the hydrographic study. Withincreased developmental activities and the setting up of fertiliser units,some effluents are being discharged into the Kakinada Bay. The baywaters are now characterized by high amounts of ammonium andnitrate which may contribute to degradation. As the present depthof the Bay is very low, there is hardly any lateral mixing of waters, as8