Since 1985, the Yangtze River Delta and the Pearl River Delta regions have enjoyed rapid development and have been China's major economic growth engines.

Yet, their counterpart - the Yellow River Delta - has remained relatively backward.

But things may be changing, as the Shandong provincial government plans to develop an eco-economic zone in the region.

The Yellow River Delta region includes Binzhou and Dongying cities, and some other counties of Shandong province, covering a total area of 26,500 sq km and a population of nearly 10 million. And it ranks top in ecological and natural resources among the three main river delta regions of the country.

According to the provincial plan released earlier this year, the province will invest 1.5 trillion yuan in the region's development during the 11th Five-Year Plan Period (2006-10), which accounts for some 20 percent of Shandong's total fiscal investment during the period.

The investment will be mainly in industry, agriculture, infrastructure, real estate and trade. But first of all, the construction of the high-efficient eco-economic zone will start from infrastructure as a base for large-scale development.

According to the plan, the region's makeover has two purposes. One is to take opportunities brought by the development of Tianjin Binhai New Area to serve the Bohai Rim. The other is to support the sustainable development of all of Shandong province.

Many economists believe if given appropriate policy supports, the Yellow River Delta will not only power the economic engine of Shandong, but also the whole Yellow River drainage area.

The Shandong provincial government has applied to the National Development and Reform Commission to list the Yellow River Delta eco-economic zone as one of the country's pilot comprehensive reform zones, according to China Business News.

However, there are still some concerns.

One is the region, unlike its counterparts, does not have a centralized city with an outstanding economic performance or resources. The Yangtze River Delta has Shanghai in its center, while the Pearl River Delta has Guangzhou, says Zhang Zhiyuan, professor from the Shandong Research Institute of Regional Economy.

This means it must find out a new way to communicate and coordinate among cities in and around the region to make better use of their respective geographical advantages.

Meanwhile, preserving the natural resources while developing the economy is also a problem for Shandong.

Located along China's eastern coast and the lower Yellow River area, most of Shandong province's land is composed of plains and low-lying lands; the remaining part is mountainous or hilly lands. Natural lakes total 1,500 sq km in size, and forests cover 20 percent of the province. There are 20 types of minerals including coal, natural gas and iron ore.

The plan says that development of the projects will be implemented separately according to the characteristics of different regions. It will restrict or forbid exploitation in some regions in order to protect natural resources.

Zhou Yaoqi, a professor from China University of Petroleum, says that the development could not rely heavily on oil exploitation, as the region did before.

"GDP growth can't be the only target, we need to pursue sustainable growth," Zhou says, adding eco-friendly, resource conservation projects can produce economic benefits as well.