Characteristics of geological hazards in South China coastal areas and impact on regional sustainable development
Prevention and treatment of geological hazards is important for the sustainable development of human society. Surface geological hazards alone caused direct economic losses of ¥3.47 billion, with 768 deaths and 785 injuries in Guangdong Province, South China, from 1994 to 2005. The major factors causing geological hazards can be categorised into three types: geo-environmental, climatic-meteorological and human activity. Accompanied by rapid economic development and population growth, human activities can cause geological hazards that are as serious as those caused by natural factors. The authors propose some suggestions for prevention and treatment of geological hazards to achieve sustainable development on the Chinese coast.
SOIL EROSION AND CONSERVATION IN YUNNAN PROVINCE, CHINA
The scale and severity of soil erosion within the headwaters of the Yangtze River in Yunnan Province are discussed. The Yangtze River rises in the western uplands of the Qinghai-Tibet Plateau and traverses 6380 km through southern and central China. The headwaters are in tectonically active and geologically unstable uplands. The basin is also generally under intensive agricultural use, mainly for rice cultivation. Hence, erosion rates are high and of increasing concern, especially considering the construction of the Three Gorges (Sanxia) Dam in the middle section. Sedimentation within the proposed reservoir could impair its efficiency and therefore soil conservation must be an integral component of basin management. Soil conservation efforts in Yunnan are reviewed and the local-scale planned approach to soil conservation is illustrated, using Dongchuan and Xundian as case studies. An ongoing runoff plot study at Yunnan Agricultural University (Kunming) is used to evaluate the effectiveness of various soil conservation measures. Maize (Zea mays) cropping treatments, typically employed in local agronomic practices, are applied to 30 erosion plots at 3 different slope angles, cultivated both parallel and perpendicular to the contour, thus simulating a range of agricultural conditions on arable slopes. Plot data from 1993-1996 suggest several suitable soil conservation measures. Erosion rates were generally lower on plots where contour cultivation was used. The mean contour cultivation erosion rate was 0.69 of the mean downslope orientated cultivation rate. Straw mulch and contour cultivation seem particularly suitable soil conservation measures. INTRODUCTION
The Inca Occupation of the South Coast of Peru
like the others, however; it forks into several nearly parallel ravines of which the largest are Huayuri, Rio Grande-Palpa, Ingenio (called Collao in ancient times), Nasca proper (the ancient Caxamarca), Taruga, and Poroma. Due to peculiarities of the local topography, the irrigated areas in Ica and the ravines of Nasca are located inland, at the foot of the mountains, rather than at the mouths of the rivers as is more usual in Peruvian coastal valleys. No sharp natural or cultural boundary separates the valley of Chincha from the valleys of Cafiete (ancient Huarco and Runahuana), Asia, and Mala, the next valleys going up the coast to the northwest. At the other end of the area we are considering, however, there is a sharp break; beyond Yauca the Andean foothills reach out to the sea, natural conditions are quite different, and there are important differences in the archaeological picture as well. The historical sources which mention the south coast are not particularly helpful, except in so far as they provide us with a few dates. To begin with, no chronicler gives an explicit account of the political organization of the south coast at the time it came into contact with the Incas. It can, perhaps, be inferred from Cabello Balboa's statements about common policy toward the Inca invaders that there was some sort of political connection between the valleys of Mala, Cafiete, and Chincha, but the connection need have been no more than a temporary military alliance. Cabello makes no mention at all of Pisco. The valleys of Ica, Nasca, and 125