Disused shrimp ponds: Options for redevelopment of mangroves

Associated with the rapid increase in the production of cultured marine shrimp has been large‐scale conversion of mangroves to shrimp ponds. Production in many regions has proved to be unsustainable, largely due to inappropriate construction methods, poor environmental conditions, overstocking, and disease. A number of shrimp ponds consequently are unproductive and lie idle. Accurate assessments of pond disuse are difficult to obtain; however, unofficial estimates have suggested that as many as 70% of ponds may be disused after a period in production. Pond construction, shrimp culture, and pond disuse lead to alterations to the physical and chemical properties of soil, hydrological conditions, and the flora and fauna composition of the pond area. The case for restoration, or rehabilitation to a sustainable use, is strong. Consideration must be given to the causes of production failure, the environmental conditions remaining following disuse, the needs and preferences of pond owners and coastal managers, and technical constraints.     

罗岭隧道下穿山塘段处理对策研究分析

罗岭隧道是广东省云浮(双凤)至罗定(榃滨)高速公路的控制性工程,其中隧道下穿山塘段为该项目的重点及难点。设计中采用"抽除山塘积水、地表注浆加固、洞内加强支护"的方案,同时辅以数值模拟计算对比有、无注浆加固情况下衬砌与围岩的变形及受力情况。现场施工过程中通过对隧道拱顶下沉、净空收敛的监测,确保该段落的安全及稳定。