Who can tell me the specific shortcomings of Hoover Dam?

1. People are most concerned about the ecological environment damage caused by the dam. Because the dam reservoir area is flooded, it will inevitably lead to the loss of natural forests, grasslands and wildlife habitats, the decrease of species and the environmental degradation of the upstream catchment area; It also led to the loss of aquatic animal and plant diversity, especially the decline of important fisheries, the loss of marine biodiversity in downstream wetlands and along rivers, harbors and neighbors; However, the impoundment of the dam slows down the water flow, which leads to the weakening of the self-purification ability of the water body, the decline of water quality and the aggravation of water pollution. However, due to the elevation of the dam, the downstream land is salinized; What makes us subvert the traditional understanding of dams is that some studies have pointed out that people used to think that hydropower has great advantages over thermal power generation in reducing greenhouse gas emissions, but this is not entirely the case. Experts made a concrete case study of a hydropower project in Brazil, and came to the conclusion that the total amount of "carbon" flowing into the reservoir is greater than that of a thermal power project of the same scale due to plant decay and catchment. Of course, due to the different conditions of reservoirs, the amount of greenhouse gases emitted by them is also different. However, on the whole, the impacts of dams on related ecosystems, especially species, are often more negative than positive, and some of them are significant or even irreversible.

Secondly, there are social problems brought by dams. Downstream fishery development, resident migration and loss of local historical and cultural resources; In addition, due to the construction of several large diversion dams on a river, the relationship between upstream, middle and downstream tends to be tense on the issue of water diversion.

Of course, there are still some dams whose economic benefits cannot make ends meet for various reasons.

With all kinds of disadvantages, we have to question this huge project that we are proud of. Even in developed countries, some dams have been stopped or removed to ensure the restoration of key water ecosystems. Norway has announced that it will stop building large dams in the future, and the United States is currently dismantling more dams every year than building new ones. Some people called for the demolition and suspension of dam construction.

2. Most of Saudi Arabia has a subtropical desert climate with an average annual rainfall of less than 200mm. The arable land area only accounts for about 2% of its land area, and 39% of the land can only be used for low-density grazing. Jizan agricultural area and Tihama plain with abundant rainfall and good irrigation conditions in the southwest are the main agricultural areas in Saudi Arabia. The government attaches great importance to agriculture, invests heavily in the construction of water pipelines, dams and other agricultural infrastructure, desalinates seawater to solve agricultural water use, adopts modern science and technology to develop agricultural production and aquaculture, and gives preferential subsidies to agricultural products. Agricultural exports account for 20% of the total non-oil exports. At present, Saudi Arabia has achieved self-sufficiency in wheat, dates and eggs. The self-sufficiency rate of grain is 98%, vegetables 85%, fruits 70%, fish 52% and meat 46%. There are 40,000 artesian wells, 52,000 drinking water wells, 220 dams, with a storage capacity of 800 million cubic meters, and a pipeline irrigation network 1000 kilometers. In March, 20001year, Shanong Water Resources Department announced the construction of 12 dam to cope with the pressure of agricultural development and irrigation. The import sources of agricultural products needed by Saudi Arabia are divided into four categories: live animals, frozen beef and mutton, and frozen chicken. The main importing countries are Australia, New Zealand, Somalia, Turkey and China; Finished or semi-finished foods such as dairy products, cheese, biscuits, dried and frozen foods. Mainly from EU countries; Due to geographical location, vegetables and fruits mainly come from neighboring Middle Eastern countries. Beans, rice and other miscellaneous grains mainly come from India, Thailand, the Philippines, China and the United States.