**4.1 Description of the study areas**

Land husbandry interventions that are suitable for hilly landscape were extensively introduced in the country since 2010 to control erosion and runoff. This strategic action has been initiated by the Land Husbandry Water Harvesting and Hillside irrigation (LWH)<sup>1</sup> project under the MINAGRI to

<sup>1</sup> Project funded by the Government of Rwanda and multi-donor organizations such as USAID, the World Bank, the GAFSP, and the Canadian International Development Agency.

*Erosion Control Success Stories and Challenges in the Context of Sustainable Landscape… DOI: http://dx.doi.org/10.5772/intechopen.96267*

boost the land productivity. The purpose was to introduce a wide range of innovations for improving agricultural practices, sustaining land management conditions and combating food insecurity by increasing rural community's livelihoods income.

As precedently discussed, the LWH project lies its focus on modernizing agricultural farming activities in hilly landscapes subjected to erosion, fertility depletion, and acidity problem. The Nyanza and Karongi sites have been selected for solving such problems in rural farming system. Nyanza 23 site is located at latitude of 2.365618°S and longitude of 29.692154°E while Karongi 12–13 sites are located at latitude of 2.0530°S and longitude of 29.468052°E, and latitude of 2.043841°S and longitude of 29.492853°E, respectively.

#### *4.1.1 Nyanza 23 characterization*

Nyanza 23 site is located in the Nyanza District of Southern Province. The site covers a good portion of Rwabicuma, Nyagisozi and Cyabakamyi and small part of Busasamana sectors of Nyanza District and Rwaniro sector of Huye District. It covers 5,659 ha as illustrated in the **Figure 13**. It comprises an irrigation dam which is supplied by Gisuma and Gasenyi tributaries of Kagondo stream and irrigates the downward part.

Climatic data from the Rwanda Meteorological Agency (RMA) in Nyanza 23 show the mean annual rainfall of 1,177 mm per year with the driest and wettest months of July and April, 7 and 190 mm respectively. Rainy seasons last from March to June and October to December, alternating with dry seasons. Although Nyanza district generally exhibits moist rainfall conditions but on-site rainfall data showed deficit of water reducing the expected optimal crop yield. Mean temperature is excellent for plant growth but the evapotranspiration values indicated the need for additional water supply (irrigation).

#### **Figure 13.**

*Location of Nyanza 23 site illustrating implemented land husbandry infrastructures and administrative sectors. Source: Author.*

#### *Soil Erosion - Current Challenges and Future Perspectives in a Changing World*

In terms of topography, Nyanza 23 catchment illustrates five distinct slope categories using the methodology of the Digital Elevation Model (DEM–30 m resolution), accessed from the United States Geological Survey (USGS) database (http://earthexplorer.usgs.gov/). Slope gradient ranges from 0–6%, 6–16%, 16–40%, 40–60%, and > 60% that respectively covered the percentage area of 10.7, 30.0, 52.7, 6.0 and 0.61 of the catchment. The range between 16–40% dominates the study area and about 2/3 of this area has shallow soils. About soil characteristics, the catchment is dominated by *Leptosols, Lixisols, Alisols, Gleysols, Cambisols, and Ferralsols* [19, 20]*.* The catchment is generally dominated by coarse textured soils up to more than 60% of the total area whereas the remaining part is also moderately fine textured soil.
