水文与水量分配报告第六章英文翻译.docx

6. Analysis on the change trend of water in project area6.1 Analysis of the changes of the annual precipitation process in project area1. For the analysis of climate change impacts on precipitation in project area, the project counties collected a series of observed data of precipitation, runoff, temperature, evaporation.2. Considering the Shouguang City meteorological data series is longer, there is observed data of precipitation, runoff, temperature, evaporation in 1959-2012, meteorological data is integral, so analyse the influence of climate change on precipitation, water of Shouguang since 1959.3. Shouguang county rainfall station during 1959 -2012, the multi-year mean precipitation is 595.3mm, the annual maximum precipitation of 1964 is 1286.7mm, the annual minimum precipitation of 1977 is 330.2mm. The annual maximum rainfall is about 3.9 times of the annual minimum precipitation. As shown in figure 6-1:Figure 6-1: The change of precipitation process in Shouguang Citys rainfall station since 1960 6.2 Assessment of the Change of multi-year mean monthly precipitation, evaporation 4. 1959-2012 years, the precipitation of multi-year average in flood season 6-9 month accounted for 73% of annual average precipitation in Shouguang City. In July and August , 2 months precipitation accounts for about 50% of annual average precipitation.5. The distribution situation of multi-year average monthly evaporation is similar as multi-year average monthly precipitation in Shouguang, but the maximum monthly evaporation appeared in June, less monthly evaporation appeared in May, followed in April. This is a crop seedling early growth period, the ground cover is not strict, crop water requirement is larger but smaller monthly precipitation, the contradiction between precipitation and requirement is more prominent, as shown in figure 6-2.Figure 6-2: Shouguang City multi-year mean monthly evaporation accounted for the proportion of annual evaporation6.3 Effect of temperature on the precipitation, evaporation6. To sum up, in the past 1960-2012 years, the temperature in Shouguang city to the upward trend change significantly. Before 1960s-1980s, the temperature was stable basic, lower than the same period in years of average temperature. From the age of 80-90 the temperature increased, the 90s temperature reached the highest value in the same period. After 2000, the temperature maintained the same level as the 90s. But the precipitation change was more obvious, from 60s to 70s was in increasing trend, the 80s for downward trend, after 90s to rise obviously. The change trend of evaporation and temperature on the contrary, after 70s with the rise in temperature evaporation decreased, but the effect lagged significantly. In the temperature significantly increased, the impact on the annual precipitation to light much. While the annual evaporation decreased significantly, as shown in figure 6-3:Figure 6-3: the influence of temperature change on precipitation and evaporation in Shouguang City7. According to the observed maximum consecutive precipitation data and the maximum daily precipitation data each month in the Shouguang rainfall station during 1981-2011, the maximum monthly consecutive precipitation appeared respectively in May, July, August and September, the number of occurrences are 2 times, 12 times, 16 times and 3 times, respectively, accounted for 6%, 38%, 50% and 9% of each month maximum consecutive precipitation. The maximum daily precipitation were appeared in 5-9 months, the number of occurrences are respectively 1 times, 5 times, 12 times, 13 times and 1 times, respectively, accounted for 3%, 16%, 38%, 41% and 3% of each month maximum consecutive precipitation. See figure 6-4.Figure 6-4: Analysis of each month maximum consecutive precipitation and maximum daily precipitation during 1981-2012 in Shouguang8. From the perspective of each month measured maximum daily precipitation maximum consecutive precipitation changes process, in 15 years from 1981 to 1995, the annual maximum continuous precipitation, maximum daily precipitation variation comparison; but in the period of 1996-2011, the annual maximum continuous precipitation, maximum daily precipitation amplitude increase. Especially in the period of 1996-2000, amplitude, value presented increased tend evidently. In 2000 the maximum consecutive precipitation, maximum daily precipitation were respectively 2691mm, 176.1mm, is the biggest year.9. The maximum amount of daily precipitation over 100mm had 6 times, all appeared after 1996, 4 of which appeared in the 2001-2011. The maximum consecutive precipitation over 100mm appeared 13 times, which appeared 10 times since 1996, accounting for 77% of the period total number. In 5 years from 1997 to 2001, the maximum consecutive precipitation more than 100mm every year; in 2001 the maximum consecutive precipitation reached 269mm, for the maximum value in the same period, as shown in figure 6-5.Figure 6-5: Analysis of maximum consecutive precipitation, maximum daily precipitation since 1981 in Shouguang City rainfall station10. The climate change, temperature rise in the influence of the total annual precipitation, at the same time also influence the temporal and spatial distribution of precipitation. Extreme weather events such as consecutive drought, droughts and floods switch sharp, heat waves appear frequently, resulting in the loss and harm is also growing. To illustrate under the impact of climate warming, the frequency and influence of extreme climate events caused have an obvious increasing trend.6.4 Effect of rainfall on Runoff11. According to the runoff data monthly of Shouguang Cha river from 2001 to 2