The problem is the lack of soil pore space in the topsoil. A healthy soil should contain approximately 50% minerals and organic matter; and roughly 25% air and 25% water. Problems start to occur when the soil clay mineral percentage increases. Soil minerals are made up of sand, silt, and clay. Therefore the higher the percent of clay, the smaller the pore size.
The solution to prevent waterlogged soil is to promote the formation of water stable aggregates. The addition of organic matter certainly is a tried and true method, especially for flower beds. Needless to say, on a large scale this can be expensive and time consuming. Before you consider the various drainage solutions around the house that are available to you, you need to find out where you can redirect the water. The primary reason why an area becomes wet or mushy is because it is lower than the surrounding areas. There are many solutions for water drainage that you can consider to make this area dry.
When your property is constructed in a low lying area like at the foot of a hill, then you need good rainwater drainage solutions. During the monsoons, rainwater will flow downwards through the slope of the hill and there might be water logging in your property. To prevent this, you need to channel this rainwater into another place. The best thing to do in such a situation is to install a dry well. A dry well in essence is just a deep pit that is dug at the lowest point in your property. It is then filled up with gravel and river stones so that the water permeates into the ground. While doing dry well construction in your property, make sure that it is located away from the structure of the house.