France sent technical equipment to help Gazans draw water from the ground. The Swiss sent blankets and plastic tarps. Mercy Corps, a relief agency, sent 12 truckloads of food. And on Tuesday all of it, including dozens of other trucks carrying sugar, rice, flour, juice and baby formula, sat in the hot sun here going nowhere. This normally quiet commercial crossing between Egypt and Israel has been turned into a parking lot of stalled, humanitarian aid, and in the city of El Arish there are even greater quantities of food, clothing and essential supplies, sitting, waiting and baking in the sun.