According to Vaastu Shastra, the Slope of the Site plays important role in designing the house and the flow of surplus around the house. Vaastu has some guidelines to aid you while Selecting the Site or Plot with the ideal ‘Slope’.
The North-East half of the plot is called the Solar [Sun] half and the South-West half is called the Lunar [Moon] half. Preferably the Solar half [Sun] should be lower than the Lunar half [moon]
In short, Vaastu recommends that always, the:
North-East corner should be the lowest
South-West should be higher than the North-East corner
As in broad the plot should be elevated in South and West directions, and declining towards East and North, so that water should flow from West to East and from South to North. Such plot is known as elephant’s back. Goddess of wealth, Lakshmi is said to live in such Plots
This type of plot brings Joy, Happiness, Good offspring and overall success in life to the habitats in the houses constructed on such plots.
On the other hand, if Sun’s place is elevated over Moon’s place, the family residing in that house will turn into poorer day by day, health problems and get entangled in unwanted quarrels, litigations and lose everything gradually.
The plot, which is elevated in the middle and shallow all around, is known as Turtle’s back. Inhabitation on such land leads to greater enthusiasm, luxuries and accumulation of wealth for the occupants.
However, any of the deficiencies observed in your plot [After purchasing] please make the plot with Vaastu complaint like elevating the South-west than North-east before constructing a house.