Hi Bushraa Shaikh,

Here are some useful links for persual.

http://mahaagri.gov.in/cropweather/agroclimaticzone.html

http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502013000200005

https://www.academia.edu/441833/Hydrogeological_studies_along_the_coastal_areas_of_Kanyakumari_to_Colachel_after_Tsunami_South_Tamil_Nadu

Infiltration to me suggest rainfall, but no increase in runoff, the water is absorbed or infiltrates into the soil.  So if this is your meaning, there are many small storms and especially in the growing season when the soils are drier, that all water is absorbed or infiltrates with no stream water response.  In the other hand, there may be periods of maximum wetness or flooding, where almost all incremental rainfall is retained in the floodwaters or moves to streams and discharged as streamflow, but probably less than 100%.  If talking about the whole storm that falls on wet soils, perhaps only 20% infiltrates.  A lot is going to depend on individual factors such as surface depressions, soils, incipient moisture, drainage pattern, stream types, gradient, etc. that can retain or detain water for longer periods so it can eventually infiltrate.  Such as a gully channel system is efficient at moving water and therefore would limit time for water to infiltrate under wet conditions, while braided streams for example are inefficient water and sediment movers, and may retain water on the valley low gradient  landscape longer, allowing more time for infiltration.  Streams with steep channels that have eroded to bedrock with steep contributing slopes may infiltrate less under wet conditions and as example, well drained, deep sandy soils are going to infiltrate more under all conditions than shallow clay soils.  So it is going to depend somewhat to your unique coastal system and types of storm severity and frequency as to how much actually infiltrates.  Also it may depend on exactly what you qualify as infiltration, if the soil absorbs water into its rooting depth and is later transpired by trees, will you count that as infiltration or do you only want to count what gets to deeper groundwater supplies?  In the dormant season, when evapotranspiration is minimal, the amount of rainfall minus streamflow should give you an estimate to consider, and if you had some wells, you could see how much they drop with time and assume that is how much is going to groundwater.  Here are a couple of papers for you.