A couple feed chickens at Leipingta Village in Ansai District of Yan'an, northwest China's Shaanxi Province, Aug. 27, 2019. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

Farmers pick apples in Yongxiang Township of Luochuan County, northwest China's Shaanxi Province, Aug. 28, 2019. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

Aerial photo taken on Aug. 28, 2019 shows a general view of Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

Aerial photo taken on Aug. 14, 2019 shows the Jinshaan Gorge in Yanchuan County of Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

A car drives on the mountain road at Zoumatai Village of Wuqi County in Yan'an City, northwest China's Shaanxi Province, June 5, 2019. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

Aerial photo taken on June 6, 2019 shows the clouds floating over Zoumatai Village in Wuqi County of Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

Aerial photo taken on Oct. 2, 2010 shows the scenery of Fenghuang Mountain in Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes.(Photo: Xinhua)

Aerial photo taken on Aug. 10, 2019 shows a view of Ansai District of Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes.(Photo: Xinhua)

Tourists take boats at Wanhuashan Park in Yan'an, northwest China's Shaanxi Province, May 6, 2008. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes.(Photo: Xinhua)

Aerial photo taken on Oct. 2, 2010 shows the scenery of Nanniwan in Baota District of Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

Aerial photo taken on Aug. 29, 2019 shows Baota Mountain in Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

Aerial photo taken on Aug. 10, 2019 shows a view of Ansai District of Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

Aerial photo taken on June 6, 2019 shows the clouds floating over Zoumatai Village in Wuqi County of Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes.(Photo: Xinhua)

Photo taken on Aug. 15, 2019 shows the wetland by Yanhe River in Ansai District of Yan'an, northwest China's Shaanxi Province. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes. (Photo: Xinhua)

Tourists enjoy themselves at Mangtoushan National Forest Park in Yan'an, northwest China's Shaanxi Province, Oct. 15, 2009. The city of Yan'an on the Loess Plateau, where 258 million tonnes of mud and sand were once washed into the Yellow River each year, has seen its landscape improve greatly. Since 1999, local government has returned 718,307 hectares of farmland to forests, increasing the local vegetation coverage rate from 46 percent in 2000 to over 80 percent at present. Data showed that the city reported fewer sand and dust days in recent years, and the annual amount of mud and sand washed into the Yellow River has been slashed by 88 percent to 31 million tonnes.(Photo: Xinhua)