China
Africa
Explore chapters and articles related to this topic
Soils with Problems Due to Anthropogenic Reasons (Degraded Soils)
Published in Manorama K.C. Thampatti, Problem Soils, 2023
Check dams: Check dams are constructed across the streams to reduce the velocity of runoff water and to entrap the sediments. Check dams are built in a range of sizes using a variety of materials, including clay, stone and cement. Earthen check dams, or embankments, can easily be constructed by the farmers themselves. There are logwood check dams, loose boulder check dams, dry rubble check dams and concrete / masonry check dams. Masonry and reinforced cement concrete (RCC) check dams are of more permanent in nature and serve the purpose of water conservation. The sluice, spillways and other regulatory structures constructed in the drains help to regulate the flow of excess water.
Analysis of Drought Factors Affecting the Economy
Published in Saeid Eslamian, Faezeh Eslamian, Handbook of Drought and Water Scarcity, 2017
Bapon S.H.M. Fakhruddin, Saeid Eslamian
Drought can be managed by preparedness and proper mitigation techniques. The measures involve accurate prediction of droughts, monitoring and assessment of the damages from droughts, and implementation of cohesive response policies and plans. The drought takes time to affect the region and this time can be properly utilized to cope with the event. Indigenous knowledge can also help fight the impacts of droughts such as by crop rotation and shelterbelts. Water conservation measures such as check dams may also be utilized to increase the water supply and groundwater level.
Erosion Sediment Control
Published in Mritunjoy Sengupta, Environmental Impacts of Mining, 2021
The most common type of grade control structure is the check dam. Check dams are short dams constructed of a variety of materials such as logs, treated lumber, stone, concrete, and synthetic materials. The check dam flattens the slope of the stream and dissipates energy. Stone or concrete is placed in the high energy area at the downstream of the check dam so as to prevent undercutting of the structure. In streams susceptible to flooding, check dams should be used with caution as they reduce flow rates and increase the chance of flooding.
Magnitude amplification of flash floods caused by large woody in Keze gully in Jiuzhaigou National Park, China
Published in Geomatics, Natural Hazards and Risk, 2021
Jiangang Chen, Wenrun Liu, Wanyu Zhao, Tianhai Jiang, Zhongfu Zhu, Xiaoqing Chen
Debris flow mitigation engineering in Keze gully was performed in 1989, and three check dams were built with a design life of 20 years (Cui et al. 2003; Cui et al. 2007). The check dams were constructed from stone blocks with cement mortar, and the foundations of the check dams mainly rest on Quaternary debris flow deposits. Because these deposits are relatively poorly consolidated, highly compressible and highly permeable and feature low strengths and bearing capacities, the check dams can easily experience uneven settlement. The effective height of slit-check dam No. 1 is 2.0 m, and the axis length of the dam crest is 12.5 m. The design aim of this dam is to block huge boulders, and it can work well after flash floods. The sidewall of check dam No. 2 is composed of many sections, and each section is connected with cement mortar. The connectivity of this technique is poor. Consequently, the deterioration of material properties and settlement of the foundation will lead to cracks and failure of the check dam with the extension of its service life. The effective height of check dam No. 3 is 3.0 m, the axis length of the dam crest is 20.4 m, and the deposition slope of the debris flow is 11%. After the flash flood, the downstream of the dam was scoured to a depth of approximately 1.29 m and the right-side wing wall was exposed to the ground, however, check dam No. 3 is still stable.
Assessment of check dams’ role in flood hazard mapping in a semi-arid environment
Published in Geomatics, Natural Hazards and Risk, 2019
Mehdi Sepehri, Ali Reza Ildoromi, Hossein Malekinezhad, Afshin Ghahramani, Mohammad Reza Ekhtesasi, Chen Cao, Mahboobeh Kiani-Harchegani
As one of the most effective flood prevention measures, check dams play a vital role in flood control (Yazdi et al. 2018; Abbasi et al. 2019). In the study area, a large number of check dams had been constructed in a concentrated fashion around the drainage networks. Given the lack of data on the storage capacity of check dams, the height of the check dams, which is directly related to their capacity, was used as an indicator for flood resistance. Regarding the role of check dams in reducing flood hazard, Eq. (2), which is the inverse of Eq. (1), was used to calculate the fuzzy scores. As shown in Figure 3, areas without any check dams had the highest fuzzy score and vice versa. The entropy values of this index are also in the range of 0–0.34. A challenging question in this regard is to see whether the flood hazard map of the region will change in the absence of any check dams. In this study, a similar property to the change-point was used to answer this question. For flood hazard mapping, a fixed map with a value of 1, which refers to areas without any check dams, was added to other indices before the construction of check dams. In the next step, after the construction of check dams and given their diminishing effect on flood hazards, a number smaller than 1 (depending on the height of the check dams) was added to other indices where the change-point occurs (Figure 4). It should be noted that the addition of a map with a constant value of 1, instead of the index map for the presence of check dam, changes the weighted entropy values of indices. Therefore, they are calculated relative to other indices.
Critical evaluation of the hydrological, biological and sociological impacts of the implementation of flood control check dams in the Upper Marikina River Basin Protected Landscape, Philippines
Published in International Journal of River Basin Management, 2023
Rej Winlove M. Bungabong, Wade L. Hadwen, Larry V. Padilla
As part of the flooding and erosion control interventions detailed in the Management Plan, a number of check dams such as gabion silt dams and earth fill (impounding) dams were targeted to be installed in the upstream of the river (MWCI, 2012). As defined in this management plan, a check dam is a ‘small dam constructed in a gully or other small water course to decrease the streamflow velocity, minimize channel scour and promote deposition of sediment’ (MWCI, 2012, p. 11). Thus, ‘porous’ check dam structure such as gabions, boulder riprap, have been recommended in the said management plan. Based on the recent report of the DENR-PENRO of Rizal, a total of 246 check dams had been constructed as of 2016. Interestingly, this approach, along with other structural measures such as dam and other water impounding facilities, has become a trend in management of other rivers in the Philippines and is considered an action which can instantaneously solve issues on flooding, river siltation, and sedimentation. Under the Public Investment Plan of the Philippines, the government allotted about 41.3 billion pesos (USD 1.2 billion) from 2004 to 2009 to implement a number of flood control and mitigation projects within the major river basins of the Philippines (CTI Engineering International Co. Ltd, 2004). However, based on the review and evaluation of the projects commissioned by the Japan International Cooperation Agency (JICA), a number of project management and implementation concerns were identified. Among these were (1) lack of baseline data and comprehensive assessment on catchment characteristics (i.e. discharge, flow, river condition); (2) lack of consultation and coordination with other sectors; (3) improper installation of a dike in the river; (4) influences of politics in the implementation; (5) unsuitable construction design and method; (6) lack of project continuity; and (7) non-allotment of funds for operation and maintenance, among others (CTI Engineering International Co. Ltd, 2004).