Study on the Eco-Environmental Water Requirements in Mid and Downstream Region of the Yellow River

Based on the definition and the classification of the eco-environmental water requirements, the minimum eco-environmental water requirements in the typical county at the mid and downstream of the Yellow River are computed. In the process, Penman-Monteith method and the method based on the theory of hydrological cycle are used. The results show that the water consumed by the eco-environment reaches 6.097 times 10⁸ m³ and 7.018 times 10⁸ m³, the average being 6.56 times 10⁸ m³. The difference between the two methods is about 13%. Comparison with other researches shows that the result is rational. The methods are reasonable and can be used in other semiarid and semi-wet region.