Wastewater riser, respectively, is the first letter of the pinyin of the words waste and stand, if it is a sewage riser, it is WL.
Note:
China's farmland drainage business and drainage technology has achieved many successful experiences, there is a greater development, but the development of various parts of the country is not balanced. In the future, there is a need to further strengthen the drainage system, establish a complete network of field drains, control the water table, improve the standard of flood control, and seriously carry out drainage tests and scientific management of the drainage system, renovate the low-yield fields, and improve the effectiveness of drainage.
Expanded information:
In order to control the water table, it is necessary to excavate inter-field drainage ditches with a certain spacing and depth. In the case of a given depth of drainage ditches to meet certain drainage requirements, the smaller the spacing of the drainage ditches, the faster the groundwater falls, and the greater the value of the drop in groundwater level in a certain period of time;
And the larger the spacing of the drainage ditches, the slower the groundwater level falls, and the smaller the value of the drop in groundwater level. In the permitted time, the requirement to achieve a certain depth of groundwater burial ΔH, the greater the spacing L1 of the drainage ditch, and the greater the depth of the drainage ditch D1; on the contrary, the depth of the drainage ditch and the spacing of the ditch is also the smaller (Figure 1). Drainage
When the crop allows a certain depth of groundwater ΔH, the depth of the last fixed drainage ditch D can be expressed in the following formula: D = ΔH + Δh + s
In which ΔH is the depth of groundwater required by the crop (m); Δh is the center of the ditch between the center of the point of the water table has fallen to the ΔH, the point of the groundwater level and the ditch level of the difference between the level of the water table, generally not less than 0.2 ~ 0.3m; s For the last fixed drainage ditch in the depth of water, generally take 0.1 ~ 0.2m.
In order to accelerate the exclusion of surface water in the field, the last fixed drainage ditch should also have a certain spacing. The spacing and the formation of field rainfall runoff process, allowable flooding time and farmland storage capacity and other factors, to be determined by the test.
In northern China, the groundwater depth is shallow, water quality is better in the region, often combined with well irrigation shaft pumping and drainage. In the vertical well pumping and drainage process, due to water wells from the groundwater aquifer to absorb a certain amount of water, in the vicinity of the water wells in the groundwater level will be discharged with the amount of water and constantly lower.
This reduction is partly due to long-term pumping wells, groundwater recharge is not as good as, consume part of the groundwater reserves, inside and outside the pumping area to produce a groundwater level drop funnel and the formation of the solid line shown in Figure 2, called static water level drop;
The other part is due to the process of convergence of groundwater to the wells occurring in the loss of the head and the production of the pumping wells from the closer the larger the value of the more. The total water level drop formed in the pumping process of water wells is called dynamic water level drop, as shown by the dotted line in Figure 2. Due to the pumping effect of water wells, the depth of groundwater is effectively increased and the evaporation of groundwater is reduced, thus preventing the soil from returning to salt.
Drainage in the use of vertical wells to take into account the case of irrigation and drainage, the spacing of the wells on the one hand, determined by the irrigation area that can be controlled by a single well output, and on the other hand, also determined by a single well to control the groundwater level requirements. In the use of vertical wells simply drainage area, the spacing of wells is mainly determined by the control of groundwater level requirements.
Baidu Encyclopedia - Standard Design for Buildings in Central and South China - Water Supply and Drainage Atlas
Baidu Encyclopedia - Drainage