Benin's renewable water resource potential is no less important. In the basement regions such as the Collines department, the hydrogeological characteristics made of crystalline rocks condition the recharge of the aquifers and therefore the durability of the boreholes drilled. The objective of this study is to determine the potential groundwater recharge zones at the scale of collines aquifer systems. Thus from planimetric data made of geological, pedological, hydrographic, slope, land use maps; satellite images and technical data from 50 boreholes, piezometric level mapping methods associated with multi-criteria analysis methods were applied. It appears from the results obtained that the aquifer system of the Hills located in a hydrogeologically difficult zone is made of a strong potential of recharge. The piezometric levels vary between around 40 m and 320 m. The highest are located in the north (recharge zone) of the department and gradually decrease towards the south to minimum values ​​of 40 m. The general trend of the flow is from North to South with domes and depressions. The main domes are in the north in the municipalities of Bantè and Ouessè. Depressions are observed south of the communes of Savalou and Dassa-Zoumè. The domes constitute the groundwater recharge zones while the depressions are the discharge zones. Recharge areas require protective measures to avoid pollution in the aquifer system.

In agroecological zone 5 of Benin, agriculture is mainly rainfed and is closely linked to the evolution of the characteristics of the rainy season. This is intended to be a scientific contribution to the determination of the annual agricultural period linked to the rainy season at the scale of agroecological zone 5 of Benin. A reliable prediction of the start and end date of the rainy season would effectively help the preparation of fields, the mobilization of seeds, labor and equipment and also reduce the risk of sow too early or too late. The model of the cumulative percentage of average rainfall and the hydrological criterion, methods based on the analysis of rainfall at the scale of the study area, made it possible to identify the periods determining the rainy season in the study area. We observe greater instabilities at the start of the seasons than at the end. This trend differs according to climatic regimes.

Growing population is a challenge for developing countries. They must resort to quality agriculture in order to meet the nutritional needs of this population. In Benin, agriculture occupies a prominent place in the socio-economic life of the population. The objective of this study is to identify from a multi-criteria approach combined with GIS, the specific areas for the cultivation of various cereals, tubers and other food crops and market gardening in order to contribute to the improvement of yields in Hills. The methodology used is based on GIS techniques coupled with multi-criteria analysis methods from data on the physico-chemical components of the soil, agricultural statistics and socio-economic data obtained in the field. The results obtained show that the hills department has a good aptitude for soybean crops and market gardening but moderately suitable in the communes of Dassa-Zoumè and Savè. In general, the department of Collines is suitable for most crops practiced in Benin. This is partly due to the knowledge that producers have of the quality of their soil, often assessed through the level of yield of the previous one.

Population growth is now causing increasing pressure on the environment. In view of the consequences that flow from it, the safeguarding and protection of ecosystems is a fundamental necessity for the biodiversity of fish species. At the scale of the Sô watershed and its tributary stream, anthropogenic actions have considerably influenced the quality of the available water resources. The purpose of this study is to assess the state of vulnerability of the water resource. From the physicochemical and bacteriological data of the water taken from three points of the outlet of the basin, various forms of water pollution have been proved. The results showed a strong variation of physicochemical parameters, a seasonal dynamics of pollution and differentiated mineralization processes. With high photosynthetic activity in the river, a high concentration of dissolved oxygen, COD, nitrates, nitrites, ammonium and other ions is observed in the dry season. The observed presence of coliforms and streptococci confirmed the state of organic pollution and bacteriological and toxicological risks at the basin scale. This situation now calls on the authorities at various levels and managers of the basins to take the necessary measures to avoid public health problems to the neighboring populations, this situation has an impact on the current development of the locality.