The JOESCO flood wall tells you that one of the following situations is a level IV response:

(1) one river system experiences one general flood every 5 to 10 years;

(2) floods and waterlogging in one city;

(3) two or more large and medium-sized reservoirs began to discharge water;

(4) major flood channels start to flood;

(5) two or more mild droughts occurred on the market;

(6) water supply in two or more large and medium-sized cities is affected by drought;

(7) the provincial meteorological disaster prevention headquarters shall launch a level II early warning for major meteorological disasters;

(8) the provincial meteorological station has issued an orange rainstorm warning, or the general headquarters for flood control and drought relief of haihe river has started level IV emergency response, depending on the situation.