NEW : U.N. is increasingly worried about flood-driven malnutrition among children . U.N. official says a `` colossal disaster is getting worse '' About 1 million additional people have been displaced in Sindh province , the U.N. says . The United Nations has warned that more than half of Pakistan's population could be affected by floods this year.
NEW : U.N. is increasingly worried about flood-driven malnutrition among children . U.N. official says a `` colossal disaster is getting worse '' About 1 million additional people have been displaced in Sindh province , the U.N. says . Authorities have ordered evacuations in the Indus River delta .