response of Evapotranspiration to Changes in Land Use and Land Cover and Climate in China
The response of Evapotranspiration to Changes in Land Use and Land Cover and Climate in China During 2001-2013
Research Purpose
The research aimed at identifying how climate change and land use and land cover changes result in changes in evapotranspiration. Besides, the study also aimed at analyzing the spatial and temporal variations of evapotranspiration in China.
Topics to discuss
- Effects of climatic factors on evapotranspiration
Sunshine duration is the number one factor affecting evapotranspiration in China. In this country, the sunshine duration is minimal, therefore reduced evapotranspiration ability to take place. During evaporation, wind speeds come in to be another factor affecting evapotranspiration, and this is because it affects water transport during the process. Over the years, studies have shown a reduction in wind speed in China. The leading cause of this reduction is due to the lessening intensity of monsoon. The relative humidity of the area relies mostly on dry or wet water surfaces. This, therefore, makes relative humidity to affect the evapotranspiration process slightly.
Just like any other country, China is also experiencing a rise in temperature average. Since the beginning of the twenty-first century, temperature average has contributed positively to evapotranspiration in the region. But still, the wind speed and sun duration tend to outweigh the average temperature hence the evapotranspiration rate even decreasing. Land use and land cover changes also affect the rate of evapotranspiration negatively. The reason being, as the population of china increases, a more significant part of the land is cleared to create room for settlement. This reduction of natural vegetation contributes to a decrease in the rate of evapotranspiration.
- Climate variability and its effects
The hydrological cycle depends on precipitation as a vital tool for water supply in the environment. This means that in some way, the precipitation rate will control the evapotranspiration of an area. There was a drought in some parts of China in the year 2009. The most affected regions were Hua Bei and Dong Bei, which contributed to further falls in the evapotranspiration rate compared to the normal years. When there is reduced land cover, that is the vegetation, and the rate transpiration lowers rapidly. Sunshine duration, wind speed, and average temperature are the decisive factors for the rate of evapotranspiration. This mostly occurs in an area where precipitation does not affect evapotranspiration. In 2012, the water logging in some parts of the country contributed to an increase in the evapotranspiration rate compared to the year 2011, where the same regions ware affected by drought.
- Ecological restoration effects on water resources
The soil evaporation rate is known to contribute a minimum percentage of evapotranspiration compared to an area covered with vegetation. The change of areas with natural vegetation converted into a settlement area decreases the rate of evaporation and transpiration with a more significant margin. Land use and land cover are affected by deforestation and afforestation of an area. Recent studies show that when land is converted into forests, the rate of evapotranspiration increases. But when a forest is cleared for other uses, the rate of evapotranspiration decreases. After the year 2003, China began investing in how to return croplands into forests, which contributed to an increase in the evapotranspiration rate. The increasing populations in china made land use and land cover have a significant adverse effect on the evaporation and transpiration. By the year 2007, China had control of desertification. This led to an increase in vegetation coverage in most regions hence contributing to increased precipitation in the country.