# How Will Rwandan Land Use/Land Cover Change under High Population Pressure and Changing Climate?
## 3 Results
### Driving Factors and Changes in Land Use/Land Cover  
In this study, 11 indicators (Figure 3) of five driving factors, namely location, soil, population, precipitation, and topography, were selected. Changes in the driving factors of LULC during three phases, namely Phase A (1990-2000), Phase B (2000-2010), and Phase C (2010-2015), were analyzed. As shown in Figure 6, changes in forest, grassland, and cropland are driven by multiple factors such as location, soil, population, precipitation, and topography; By contrast, changes in wetland, water, urban land, and unused land are mainly driven by a single factor, and supplemented by other factors. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Land Use Type**} & \multicolumn{6}{c}{**1990**} \\ \cline{2-9} \multicolumn{2}{c}{} & **Forest** & **Grassland** & **Cropland** & **Wetland** & **Water** & **Urban** & **Unused** \\ \hline \multirow{8}{*}{2015} & Forest & 3370.27 & 301.13 & 612.11 & 29.87 & 5.51 & 2.05 & 1.13 \\  & Grassland & 1226.14 & 2940.45 & 502.29 & 117.45 & 5.72 & 0.86 & 23.74 \\  & Cropland & 6065.24 & 2081.78 & 5034.99 & 220.50 & 27.56 & 5.62 & 10.48 \\  & Wetland & 84.89 & 50.92 & 11.80 & 703.26 & 36.87 & 0.39 & 0.03 \\  & Water & 21.12 & 9.75 & 6.45 & 24.83 & 145.911 & 0.01 & 0.00 \\  & Urban & 124.41 & 59.37 & 70.56 & 1.18 & 0.19 & 107.42 & 0.15 \\  & Unused & 2.00 & 0.47 & 3.34 & 0.03 & 0.00 & 0.04 & 0.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Transfer matrix of land use types in Rwanda from 1990 to 2015 km\({}^{2}\). Figure 5: Land use area of Rwanda from 1990 to 2015. During Phases A and B, precipitation had the highest contribution rate to forest change, followed by population, topography, location, and soil. During Phase C, topography had the greatest contribution rate (25.5%) to forest change, followed by population (23.00%), precipitation (21.84%), location (16.89%), and soil (12.73%). During Phases A and B, population had the highest contribution rate to grassland change, followed in decreasing order by topography, precipitation, soil, and location. During Phase C, precipitation became the largest force driving grassland change, with a contribution rate of 26.45%; it was followed by population (23.97%), topography (21.82%), location (16.54%), and soil (11.22%). The driving factors contributing to cropland change were population, precipitation, topography, location, and soil, in decreasing order of their contribution rate. Population had the highest contribution rates in Phases A (26.89%), B (27.90%), and C (29.19%); its contribution exhibited an increasing trend. Precipitation had the second-highest contribution rates to cropland change in Phases A (20.98%), B (21.65%), and C (23.51%); its contribution also exhibited an increasing trend with time. Topography had the third-highest contribution rates to cropland change in Phases A (23.72%), B (22.91%), and C (18.72%); its contribution rates exhibited a decreasing trend with time. The contribution rates of topography to wetland change during Phases A, B, and C were as high as 41.56%, 43.32%, and 45.54%, respectively; they demonstrated an increasing trend, indicating that topographic factors were the most important factors limiting wetland change. Topography, precipitation, and location were among the factors driving the change in water. Of these, the contribution rates of topography during Phases A (43.68%), B (55.54%), and C (25.45%) were the highest. Precipitation had the second-highest contribution rates during Phases A (16.32%), B (10.17%), and C (21.17%). The contribution rate of location during Phase C increased sharply to 29.21%, making location the main factor driving the change in water during Phase C. Urban land change was mainly influenced by population. During Phases A, B, and C, the contribution rates of population to urban change were 72.54%, 79.38%, and 55.24%, respectively. Moreover, the contribution rates of precipitation and soil to urban change increased gradually with time.