108
7 Effects of Conservation Practices …
Fig. 7.3 A check dam and a dam farmland in the Nanxiaohegou Catchment
study, in the Loess Mesa Ravine Region of the Loess Plateau, check dams (Fig. 7.3)
had the best effect on controlling soil erosion, followed by the terrace farmlands,
and then the forest lands and the grasslands. More than 90% of the retained soil
and water, especially soil, was accomplished with the dam farmland, although it
occupied only 2.3% of the total area of all conservation practices. Similar results
were also obtained by other researchers. For example, it has been reported that at
the global scale, sediment loads are chiefly reduced thanks to sediment trapping by
dams (e.g. Minella et al. 2009; Syvitski et al. 2005; Walling 2005). Xu et al. (2004)
has also pointed out that the check dam system in gullies was the most effective way
to conserve soil and water on the Loess Plateau. On the whole, as a representative
gully control practice of conserving soil, water, and nutrients, the check dam is much
more preferred.
7.4.6 Future Research Scenarios
Toward future planning, more studies are still needed for this subject, including:
(1) Observation of water quality of the groundwater in the selected catchment and
the runoff through the outlet of the catchment. Other than the amount of retained
nutrients, the nutrient contents of the groundwater and the runoff are the most direct
indicators reflecting the effects of conservation practices on water environments.
Nevertheless, few observation data on water quality have been obtained until the
7 Effects of Conservation Practices …
Fig. 7.3 A check dam and a dam farmland in the Nanxiaohegou Catchment
study, in the Loess Mesa Ravine Region of the Loess Plateau, check dams (Fig. 7.3)
had the best effect on controlling soil erosion, followed by the terrace farmlands,
and then the forest lands and the grasslands. More than 90% of the retained soil
and water, especially soil, was accomplished with the dam farmland, although it
occupied only 2.3% of the total area of all conservation practices. Similar results
were also obtained by other researchers. For example, it has been reported that at
the global scale, sediment loads are chiefly reduced thanks to sediment trapping by
dams (e.g. Minella et al. 2009; Syvitski et al. 2005; Walling 2005). Xu et al. (2004)
has also pointed out that the check dam system in gullies was the most effective way
to conserve soil and water on the Loess Plateau. On the whole, as a representative
gully control practice of conserving soil, water, and nutrients, the check dam is much
more preferred.
7.4.6 Future Research Scenarios
Toward future planning, more studies are still needed for this subject, including:
(1) Observation of water quality of the groundwater in the selected catchment and
the runoff through the outlet of the catchment. Other than the amount of retained
nutrients, the nutrient contents of the groundwater and the runoff are the most direct
indicators reflecting the effects of conservation practices on water environments.
Nevertheless, few observation data on water quality have been obtained until the