Baoshun WANG, Xianguang MA, Min FENG, Lei WEI, Yan YANG

1. Institute of Land Resources and Sustainable Development, Yunnan University of Finance and Economics, Kunming 650221,China;

2. Planning and Design Institute of Land and Resources of Yunnan, Kunming 650216, China

Southern China is always impressed on Chinese people as"a land abundant with water".Nevertheless, confronted by severe droughts in Yunnan and Guizhou provinces, both of governments and Chinese people seem to be at a loss what to do, for the concerning area and influence are so extensive that has exceeded drought-related researches available. Therefore,drought-prevention and disaster-reduction has become a key strategic problem guaranteeing crop,eco-environment, water resources, and even national securities[1].It is obvious that a serious review and research on drought becomes necessary.

Meanwhile, a conclusion has been made on drought causes in Yunnan Province that global warming and El Ni?o are dominant factors[2],but ecological unbalance caused by ecoenvironment destruction should be considered as well.What’s more, besides natural factors, eco-environment deterioration by human activities, including deforestation, blind construction of water conservancy project, and overdevelopment of resources, is a major cause based on further exploration on destruction of eco-environment in Yunnan Province[2].

Nevertheless, it is a tradition that people excessively rely on constructing diversion works or conducting artificial rainfall at drought, which would possibly result in secondary destruction on eco-environment if misused,forming a new ecological unbalance,deteriorating drought, and leading to a vicious circle (Fig.1). Hence, it is necessary and urgent to reduce ecological pressure and restore eco-balance,from the perspective of the effects of man-earth relationship on drought, in order to reduce/prevent disasters basically and advance the change from drought relief after disasters to drought prevention before disasters.

With consideration of researches available on control and reduction of drought and other disasters in China,highlights are given to regional drought-occurrence rules[3-5]and causes[6], technology in preventing disasters[7-9],risk management of agricultural drought[10]and evaluation on drought prevention, which provides scientific references and methods in terms of drought prevention and disaster reduction, especially in prevention of agricultural drought. In the long run,less attention is paid to disaster prevention from man-earth relationship of these researches, and therefore, the problem can not be resolved fundamentally. It can be concluded that to consider and explore thoughts and countermeasures on drought and disaster prevention in terms of man-earth relationship becomes an irreversible trend for construction of ecological civilization and drought prevention and disaster reduction.

Man-earth Relationship and Droughts Occurring Recently in Yunnan Province

Definition and evolution of manearth relationship

Man-earth relationship refers to the relationship between human activity and geographical environment, on the premise of appearance of human beings, with human labor as a means and material technology as an intermediary[12]. Based on a specific territory,the man-earth system is a dynamicstructure physical system formed in a specific region in the process of interplay[3].Hence,the man-earth system is a synthesis of society and natural environment integrating geographical environment and human activities.

It should be recognized that both of connotation and denotation of manearth relationship is developing upon time. In early stage, for instance, because of a small population and undeveloped economy, people highly rely on nature. As population increases,and social, economy and technology advances, natural resources are increasingly exploited and developed,which reduces absolute quantity of natural resources, as well as relative quantity compared with social development, leading to destruction of ecology,pollution on environment,and conflict between human being and environment.Hence, a coordinated development of people and earth appears accordingly. However, during the history process, the recognition on human-earth relationship tends to be volatile upon schools,covering ancient man-earth relationship, determinism theory of geographical environment,dualism, environment probabilism,adaptation theory,human ecology,determination theory of productive relations,voluntarism,and sustainable development[13].

Currently, although droughts can not be completely prevented, it is necessary to recognize the occurrence and development of drought, as well as the concerning damages on environment in order to take countermeasures and reduce loss. After all, human beings should learn how to coexist with the natural disasters and keep away from timely to minimize loss of life and property. As for prevention of drought disaster,it is an important part to explore the fundamental way from the perspective of coordination of man-earth relationship.

Recent droughts occurring in Yunnan Province

Drought is one of natural disaster the most serious in Yunnan Province,with a high frequency and an extensive coverage. For example, average 50 counties suffer drought yearly in Yunnan Province[14]. The research made by Huang[15]based on drought information during 1950 -2002 indicated that average influential area of drought reached 354 500 hm2in Yunnan, of which over 30% crops in farmlands at 170 400 hm2were affected.In general,crop loss in the province averaged 306 400 t yearly. Since the 1980s, in particular, average area under influence of drought increased to 560 000 hm2,and even over 700 000 hm2in the year with serious drought[16]. For instance,from November 2009 to March 2010, Yunnan experienced the most serious drought and direct economic loss achieved 12 billion yuan[17]. According to disaster classification proposed by Shi et al.[18], the drought occurring in spring in Yunnan has reached severe disaster in terms of occurrence frequency, and direct economic loss. From the research conducted by Huang and Zhang[19]on the area influenced by drought from 2000 to 2008 in Yunnan, the drought areas tended to be volatile, of which the minimum was 206 000 hm2, and the area changed the most significantly in 2005 by 1.189 million hm2. In addition to that,as shown in Fig.1, the affected area by drought in Yunnan Province kept increasing in the 16 years, and the growth reached the peak in 2010 at 2.295 7 million hm2.

It is obvious that successive droughts have caused great loss on Yunnan Province. In accordance withstatistics, since October 2009, 16 prefecture-level divisions as well as 129 county-level divisions all suffered drought disasters in terms of forestry.Specifically, the withered forests reached 1.88 million hm2, and shrubs in karst regions withered in large areas. What’s worse, pest disaster in forests is deteriorating. The affected area in 4 years reached 1.311 3 million hm2, with the area suffering 30% crop loss at 450 700 hm2and direct economic loss at 3.3 billion yuan.Additionally, forest fire becomes more frequently due to drought.In 2012,for example, totaling 299 forest fires occurred in Yunnan Province,and affected forests reached 2 500 hm2, which grew by 160%and 260%.Since winter in 2012,782 000 hm2crops have been affected in Yunnan Province, the area with 30% crop affected reached 358 000 hm2, and the area with 80%crops affected at 85 300 hm2. On the other hand, the affected forest area reached 1.554 1 million hm2,and direct economic loss reached about 10 billion yuan. According to data in Water Resources Department of Yunnan Province,until April 17, 2013, 11 cities in Yunnan were hit by droughts, of which some suffered severe drought,resulting in dry-up of 323 rivers and 331 reservoirs.Consequently,12.448 9 million people are affected, and dysdipsia became popular among 3.423 8 million people and 1.689 1 domestic animals, so that 2.697 7 populations are in need of help[20].

According to information above, it can be concluded that drought disaster is not a short-term or an extreme small-probability event, but a high-frequency and strong disaster with a large area[6]. Therefore, it is of importance and significance for social and economic sustainable development in Yunnan Province to Prevent drought and reduce disasters in a scientific way.

Dialectic Analysis on Drought Prevention and man-earth Relationship Coordination

Regional ecological changes in Yunnan Province

Under influence of human activities, such as forest destruction, farming in steep slopes, over grazing, irrational development of resources, ecosystem is deteriorating, and environment quality is degrading. Because natural geographical environment is a complete complex,ecological changes occur in the environment system, and it is necessary to analyze ecological changes in Yunnan Province in the context of southwest region.

Sharp decline of forest, destruction of natural vegetations, and degradation of regional ecosystem

Since the 1950s, forest resources have undergone excessively exploitation,resulting in serious destruction on forests and sharp decline of forest coverage[21].On basis of statistics[22],in western regions, natural forests in Sichuan and Yunnan boundary are the most seriously damaged and unit stock volume of forest decreases over 2.5% yearly. In Xishuangbanna Dai Autonomous Prefecture, forest area reduced by 230 000 hm2during 1959-1980 and forest coverage rate dropped from 54% to 29%[23]. The decreasing of forests, however, poses a threat on biodiversity and eco-environment(Table 1)[11].

Deterioration of water and soil loss

Resulting from low forest coverage,excessive exploitation of forests and reclamation of lands, surface vegetation of soils drop substantially, and the function of mountain regions declines in terms of water conservancy and adjustment, deteriorating water and soil loss. According to statistics[24], water and soil loss became prominent. For example, the area of water and soil loss reached 134 000 km2, representing 35% of provincial area and the eroded soils totaled 510 million ton yearly, accounting for 1/10 of national loss. Water and soil loss caused by slope cropland proves the severest,taking up to 30%of water and soil loss areas and 40% of water and soil loss quantity. Generally speaking, water and soil loss has caused deterioration of eco-environment destruction and living conditions.

Excessive exploitation of mineral resources and destruction on ecoenvironment With social and economic development, humans’ demands on mineral resources are growing, and excessively exploitation on mineral resources in Yunnan Province has led to destruction on ground vegetation, landslide and debris flow. For example, unscientific construction of mining engineering possibly causes landside and irrational piling of mineral wastes would shape unstable slopes, providing materials for natural disasters, such as debris flow.

Irrational construction of projects and change of eco-environment

Yunnan Province is generally a mountainous province, and most lands should be leveled at road construction or pipeline paving, so that original shape or structure of slopes has been changed, possibly resulting in landslide and collapse. Meanwhile, hydroelectric development projects are much more in Yunnan,and water level might undergo sharp growth or decline due to improper site selection,producing uplift pressure and dynamic water pressure, which would lead to landslide[11].In addition to that,construction of roads and reservoir would produce construction wastes, contaminating environment and causing ecosystem imbalance.

The dialectical relationship between drought prevention and manearth relationship

Ecosystem is a dynamic system in a development process. Given abundant time and stable supply of energy, the ecosystem would develop oriented by a specific trend in terms of species diversity, structure complication, and function perfection until a mature state. Actually, an ecosystem is able to maintain a stable and balance state, with self-adjustment capacity.However,it is notable that such self-adjustment is allowed only within acertain extent, which would be limited or even disappear once the system change exceeds ecological threshold.

Basically, discordant man-earth relationship results in unbalance of original geographical environment,forming a new balance, which actually intensifies, instead of limiting, the changes caused by factors, and deteriorates ecological destruction.

Because of long-term irrational development of natural resources in Yunnan Province, ecological disasters increase, with a high frequency, and high risks, leading to destruction on eco-environment and unbalance of ecosystem. When drought occurs, the adjustment of an ecosystem would weaken due to ecological unbalance,which actually exacerbating adverse effects of droughts. After the disaster,what’s worse, secondary disasters are prone to occur, including debris flow, water and soil loss, desertification,biohazard and life loss, causing a vicious circle. Such a vicious circle would inevitably break original ecobalance, changing climate components in a region and affecting human existence and development(Fig.2).

Countermeasures and Suggestions on Preventing Droughts and Disaster Reduction based on Manearth Relationship

To establish a harmonious coexistence concept of man and water to protect eco-environment

It is important to promote coexistence concept of man and water among people and rectify irrational idea and action of water. Water is rare resource and every drop of water should be made full use of, which should be propagandized, laying foundation for drought prevention and disaster reduction.

To increase vegetation area, enhance forest coverage and improve climate

It is recommended to plant trees or grasses on gentle slopes and return farmlands to forests, and strictly control felling to guarantee forest coverage, in order to improve ecosystem function in terms of water conservancy and adjustment, reduce water and soil loss,and to improve dry climate.

To protect soil reservoir and improve regulation function

It is crucial to protect farmlands,improve soils by deep tillage, increase soil permeability,and enhance regulation of sol reservoir in order to reduce water loss and relieve drought damages. Because of special soil properties in plateau in Yunnan Province,soil reservoir in Yunnan is characterized by large storage capacity and strong regulation, which plays a key role in drought prevention for Yunnan Province[26].

To advance natural rainfall recycling and improve use and transform rates of rainfall

It is notable that to develop and adopt rainfall accumulation system to intensify accumulation and use of rainfalls and snows to transform into water resources for drinking, which provides a new water source. What’s more, the method has little effects on eco-environment and plays an active role in maintaining eco-balance and advance virtuous circle of ecosystem.

To restrict development of waterconsuming industry to guarantee rational use of water resources

With advancement of urbanization and industrialization, water-consuming industries are much popular in different regions,deteriorating water risks in China[27].Hence,it becomes necessary to restrict iron and steel industry, flood irrigation, and high-consumption service industry of water. For example,the industries above should be restricted or forbidden at approving to control water from economy, politic and law constructions and to guarantee rational use of water.

To adjust water actively and promote intensive use of water resources

In the long run,it is urgent and effective to improve water resource into a part of national strategic resources for further use and management from macro-perspective. For instance, water price can be adjusted as per market mechanism, involving ladder water price and taxation on waste water,and index-based control can be used if necessary to guarantee strict use of water and make dynamic management on regional water.

Conclusions

On basis of man-earth relationship, it is important to well consider harmony development between man and nature, establish the thoughts of respecting nature and protect nature and make full use of water oriented byman-earth relationship.

The research analyzed causes of secondary disasters of droughts and proposed countermeasures,such as harmony coexistence and development of man and water, protection of eco-environment and water adjustment. Furthermore, the adverse effects from droughts minimized on basis of coordinated manearth relationship.

It is notable that the research explored the relationship of man-earth coordination and drought prevention from the perspective of logical relationship and further exploration is requiring on the effects of man-earth relationship coordination on drought prevention.

Acknowledgement

We thank the communication chances provided by Cross-strait Water Treatment and Sustainable Development Seminar and amendments proposed by experts in 2013.

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