At present,most of the undeveloped natural resources in the world are mainly distributed in tropical and subtropical zones, one of wbica is low-lying land resources.The total amount of tropical and subtropical low-lying land is estimated about 2 million km2 and about 6000 of that are distributed in three regions:the three islands of Indonesia in Southeast Asia(500 000 km2),Sudan Zaire and Chad Lake Area in Africa(500 000 km2) and Colombia in South America(200 000 km2).Crops can grow all the year round with high temperature in tropical and subtropical zones,and the low-lying land there can be developed and produce a large quantity of foods to feed a great number of people.
The types, features and causes of natural disasters are discussed in this paper.Natural disasters are divided into meteorological disaster, land disaster, oceanic disaster, biological disaster, astronomical disaster and man-made natural disaster.It is considered that natural disasters, the formations of which not only depend on natural changes but also on human activities and social-economic environment, are the synthetical reflections of nature-economy-society.Natural disasters have the characters of regionlism, periodicity, masses, chains and sociality on the basis of the laws of their formations.The main natural disasters and their damages in China are also analysed, laying emphasis on drought, flood, typhoon, earthquake, mountain disaster, dust and desertification, cold disaster, intensive convection storm, forest fire and plague of insects and mice.Finally, some basic problems of natural disaster research are discussed, including the basic theories of calamities, natural disaster monitoring technique and assessment, disaster information and management, disaster-economics and disaster-sociology.
The Dongjiang basin in Guangdong Province consists of fourteen counties(cities), where there are 3 434 km2 of gentle slope platforms,accounting for 9.7% of the total area of the basin.According to their lithologic and geomorphologic features,the gentle slope platforms can be classified into 6 kinds and 11 types.The distribution of each type as well as its features and developing conditions are discussed in detail.The basin is divided into 3 districts for development of the platforms according to natural conditions and social-economic conditions:(1)Northern district,mainly for developing forestry and agriculture,partly for city-town and traffic construction.(2)Middle district, mainly for developing modern and intensive commodity agriculture.(3) Southern district,mainly for capital construction and for the development of corral livestock farming.
The hydrology of the Pearl River(Zhujiang) Delta is characterized by(1)rich annual precipitation that is 1600-2300 mm on average;(2)abundant river flow with mean runoff amount of 336 billion m3 a year,which is uneven in temporal distribution;(3)low annual mean sediment, but high suspended load that reaches 88.72 million tons a year due to a great volume of runoff;(4)weak tidal range and strong storm surge.The main features of the water resources in the delta are as follows:(1)they differ greatly in various areas and distribute unevenly in a year.Dry and wet seasons are evident;(2)guest-water resources are very abundant;(3)the river level is affected greatly by the change of tide.Some problems in the development of water resources,such as the waterflood and waterlogging calamities in wet seasons,the water pollution in main water-ways,and the water supply to cities and towns,are discussed.The author suggests that the comprehensive utilization of the water resources be improved and effective measures of water consevancy and management be taken.
During 1988-1989,a synchronus observations of the pH values of precipitation were taken at stations of ]iuxian Mountain(1650 m a.s.l.),Pingtan Island(32.5 m) and Fuzhou City(83.8 m) in Fujian Province.The result shows that:(1) Over Jiuxian Mountain,the pH value of serial precipitation varies from 5.00 to 7.00, the average pH value is nearly neutral(pH=5.90),the rate of acid rain is 1000,for Pingtan Island, the pH value varies from 3.43 to 7.15 with an average of 4.49.The acid rain rate is 57.7% and 10% for strong acid rain;for Fuzhou City, the pH value varies from 3.30 to 6.99 with a mean of 4.25,the acid rain rate is 89.4% and 33.3% for strong acid rain.(2) The pH values of precipitation are mainly determined by the local pollution condition.With the increment of the city population density and the development of city industry, the acid rain frequency increases and the pH mean value decreases.(3) The pH magnitude of precipitation is closely related to the pollution condition in connection with wind direction and weather condition over observational station.If the station is controlled by stationary front or cold front,acid rain is serious and its frequency increases, if controlled by high pressure,the frequency of acid rain decreases.
The coastal economic and technological development zones should take the development of the export-oriented economy as strategical goal because it is set by the pattern of China's open policy.The zones have advantages of economic geographic conditions, easily accessible locations,abundant technical forces and solid industrial foundations supported by cities.Some measures to speed up the export-oriented economy in the development zones are put forward in this paper.
The foundation of science and technology garden in Changsha-Zhuzhou- Xiangtan triangle region will help to bring the role of high and new technological industry of the three cities into full play, and strengthen the function of the three cities as a main growth pole in Hunan Province, which not only can aggregate advantages of extragreat city, but also can isolate three cities reasonably and avoid the disadvantages.The triangle region has wide space, good location and environmental conditions.The infrastructure in three cities has been much improved, and the socio-economy has reached a middle developed level.All in all, there essentially are conditions to go into high and new technological development term.The authors suggest that the development of the garden coincide with that of the high and new technological industry region in Changsha, urban construction in the three cities, and the mainstream of the Xiangjiang River.Capital, technology, and talented persons be attracted through various ways, and an efficient and authoritative administration organ be founded.An overall plan for the garden be worked out, The garden be developed step by step, and the stretches about 25 km2 from Yijiawan to Heishipu be developed in the near stage.
The tropical rainforest in Xishuangbanna is estimated to consist of more than 3000 species of seed plant pertaining to more than 1000 genera and about 180 families.Based on the comprehensive analysis of the distribution of taxa in two representative communities of the rainforest, the deduction is given as follows: the families, genera and species off tropical distribution take up about 80%, 94% and more than 90% of the total of the flora respectively; of which the genera and species of tropical Asia take up 33%-42% and about 74% of the total respectively.The flora is explicitly of tropical in nature and as a part of tropical Asian flora.Oceured at the montane habitates of northern margin of tropical SE Asia, the flora also embodies conspicuous characters of marginal tropics.Xishuangbanna is geographically a transitional area from true tropics to subtropics and an ecotone where several floristic elements, such as that of Indo-Malaysia, that of S Asia or S Himalayas, and that of Indochina-S China and S China mingle.The flora is therefore endowed with the characteristics of floristie ecotone.
According to the climate conditions for sisal hemp planting,six climate factors and five grade indexes are chosen for appraisal of eco-climate region.The subordinate function of each factor in different grades is formed respectively.The climate conditions of sisal hemp planting in 131 representative points of five provinces in South China(Guangdong, Guangxi,Fu jian,Yunnan and Hainan) is appraised by fuzzy comprehensive appraisal method.Five grades of regions are delineated:the favourable planting region,the suitable planting region,the plantable region,the unsuitable planting region and the unplantable region.The result of the appraisal will provide an objective scientific basis for rational sisal hemp planting in South China.
Shibachongxi is an undeveloped natural landscape area,located in Minhou County of Fujian Province.There is a lot of good scenery in the area,such as streams,peaks, waterfalls,rockpillars,caves and so on.Situated in the volcanic rock zone of coastal area of Fujian Province,Shibachongxi developed a lot of faults and volcanic organizations,of which many sights are seldem seen in other volcanic zones.From the view of geology,it was the hard volcanic rocks,dense faults,volcanic organizations and surface dynamics that built the special landscapes.Shibechongxi is not only in good views of landscape but also has the worth of scientific investigation because of its special volcanic organization.
The basic conditions for development of Danxia Landform are.(1) There are coarse clastic rocks with not very high carbonate content in conditions of damp and hot climate;(2) The earth crust there has lifted for hundreds metres since Neotectonic Movement and the area is mostly of high hills or low mountains today.Danxia Landform is characterized by the red precipices.In xinning County there are many Danxia natural bridges, of which the span of Celestial Bridge is 64 m, ranking the first in China.
Under the subtropical humid monsoon climate conditions,Huaihua region in West Hunan is rich in water resources.There are 3 467 000 kW of hydro-power reserves in theory in the region,of which 580 000 kW has been developed.Some suggestions for the development of water resources in Huaihua region are put forward:1) make step development of the arterial river,building Gaoqitan and Chenshui power stations;2) improve Longtan water and electricity base and do well water and soil conservation in the areas of the reservoir and water sources;3) develop paddy field and water conservancy project and make a good job of water supply to cities,promoting the development of industrv and agriculture.
Mali is a country with the most developed red series of rocks and the Danxia geomorphology in west Africa.Having an area of around 360 000 km2,the red series of rocks cover nearly one third of the territory of Mali,and constitute greater part of the plateau,in which the area of high plateau of 110 000 km2 is composed principally by red sandstone and conglomerate,thus foming the vast expanse of developed Danzia geomorphology in Mali,distributing from the West and the South right up to the East.Based on field work and from the angles of geological history, structure and Paleo-environment,the evolution of Danria geomorphology and its characteristics of famous red sandstone plateau and mountain in Manding,Dogon,Hombori of Mali are analysed.and examined in this paper.According to stratigraphical timescale,they are part of Pre-Cambrian;judged by the environment of evolution,they are formed in the tectonic movement taking epeirogenic movement as the dominant factor and under an ancient dry geographical condition;in accordance with the topography,they are fully developed possessing various forms and very developed grand cliff.As compared with Danxia geomorphology of China,they are noted for their old stratigraphic age,continuous distribution over a grand area and magnificent form,these are of great value for study.
