I think there is considerable research in this area. Essentially you want degradation rates, adsorption/adsorption, hydrophilic/hydrophobic, and soil properties to movement of the pesticide. This will be an extensive literature review (possibly a good sized book if you include all pesticides). You will need a university library to gain access to the older literature.

Typing in "pesticide leaching model" as a google search yields 957,000 hits. The top two hits reference PEARL, GeoPEARL, and KTURF models for soil leaching of pesticides. The existence of such models suggests considerable knowledge about the fate and movement of pesticides over and through soils in regards to the physical and chemical properties of the pesticide and the soils. 

Thank you Timothy Ebert for your kind reply.

Due EU directives that limit pesticide concentrations in groundwater, all regulatory approvals or renewals require experimental demonstration (backed by modelling) of leaching potential. As Timothy pointed out there is a mountain of data and numerous models available and the earliest models (such as PRZM and LEACHP) date back to 1980's / 90's). Because there is no single value for many of the input parameters such as degradation half life and partition coefficients, it is useful to run Monte Carlo type simulations with range of available inputs to get a good handle on risk to GW etc. USEPA website has good info on models available.

There is a possibility to collect the leachate and clean the water collected from any type of chemical.

The big risks are soluble chemicals that are not strongly sorbed, on sandy soils with underlying aquifers that are used for drinking or irrigation water.

As we know that we can not always prevent chemicals that are needed for crop production from reaching the soil, the best approach is to collect the leachate before reaching the aquifer and take the chemicals out and save the water for reuse. We have a first design system to do it.

Hi Pallavee

You can find helpful references on attachment 1

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjsns6szbXWAhUkLsAKHe6yCooQFggsMAA&url=https%3A%2F%2Fwww.iupac.org%2Fpublications%2Fpac%2F1995%2Fpdf%2F6712x2109.pdf&usg=AFQjCNGZI7FlII8Alvb0GibH32GVbCsv9w

2

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjsns6szbXWAhUkLsAKHe6yCooQFgguMAE&url=https%3A%2F%2Fwww.diva-portal.org%2Fsmash%2Fget%2Fdiva2%3A799629%2FFULLTEXT01.pdf&usg=AFQjCNF3QmL7CsUgHBfLJsupNh8w5q8Pew

3

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwjsns6szbXWAhUkLsAKHe6yCooQFgg3MAI&url=http%3A%2F%2Flink.springer.com%2Fchapter%2F10.1007%252F978-94-011-0962-8_40&usg=AFQjCNFDEXp_VbzCEeDeX10xf2k_FzJ5hw

Models will not stop the leaching. Better to prevent pesticides from touch the soil surface

and pump out the leachate, clean it and reuse the water.

4

https://books.google.com/books?isbn=2738009220

5

https://www.pearl.pesticidemodels.eu/pdf/vreepeel_2.pdf

6

https://www.pearl.pesticidemodels.eu/pdf/cost66.pdf

7

https://smartech.gatech.edu/bitstream/handle/1853/32069/TsirosI-ZakikhaniM-91.pdf

8

https://onlinelibrary.wiley.com/doi/10.1002/ps.2780310311/full

9

https://web.tuat.ac.jp/~pochi/MyPublication/Papers/16JARQmodelreview42-01-03.pdf

10

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&ved=0ahUKEwjsns6szbXWAhUkLsAKHe6yCooQFghgMAk&url=http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2F0304380094001367%2Fpdf%3Fmd5%3Df5d885f9651d2537f08a3c221cd12394%26pid%3D1-s2.0-0304380094001367-main.pdf&usg=AFQjCNGs1bLQGasxcy7neEA9liuwkkdLnw

11

https://web.tuat.ac.jp/~pochi/MyPublication/Papers/16JARQmodelreview42-01-03.pdf

12

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=12&cad=rja&uact=8&ved=0ahUKEwiNquHI1rXWAhXpBZoKHcGODhM4ChAWCCswAQ&url=http%3A%2F%2Fwww.scielo.br%2Fscielo.php%3Fscript%3Dsci_arttext%26pid%3DS0100-69162011000500014&usg=AFQjCNHCCBGIE1r1_IiYNcQ3Gz_kjO58Yw

13

https://www.pfmodels.org/downloads/ID012.pdf

14

https://onlinelibrary.wiley.com/doi/10.1002/ps.2780310311/full

15

https://www.borenv.net/BER/pdfs/ber8/ber8-031.pdf

16

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=16&cad=rja&uact=8&ved=0ahUKEwiNquHI1rXWAhXpBZoKHcGODhM4ChAWCEgwBQ&url=https%3A%2F%2Fwww.researchgate.net%2Fpublication%2F223392932_A_European_test_of_pesticide-leaching_models_Methodology_and_major_recommendations&usg=AFQjCNFEkdpWIA2DXt2ANSFNyJS3IYs25w

17

https://dl.sciencesocieties.org/publications/jeq/pdfs/20/2/JEQ0200020425

18

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=18&cad=rja&uact=8&ved=0ahUKEwiNquHI1rXWAhXpBZoKHcGODhM4ChAWCFMwBw&url=https%3A%2F%2Fec.europa.eu%2Ffood%2Fsites%2Ffood%2Ffiles%2Fplant%2Fdocs%2Fpesticides_ppp_app-proc_guide_fate_soil-persistance-1997.pdf&usg=AFQjCNGGDBCJbJqEKnysBLmmo6QR0WkbhA

19

https://dca.au.dk/fileadmin/DJF/DCA/Forside/DCArapport62.pdf

20

https://books.google.com/books?isbn=146154078X