Generally speaking, I wouldn't advise trying to survive a SHTF scenario down here, but the Karankawa did manage to scratch out a living.....
Water will be your biggest problem. The Nueces River does run down here, but it is brackish all the way to the low water dam at Labonte Park, just as you enter Corpus Christi from I-37. Oso Creek also runs along the southwest side of Corpus Christi, and it too is brackish for quite a distance upstream.
The area is considered "semi-arid", and rightly so. The average annual rainfall for the area is only 32.26 inches, with September being the wettest month at 5.03 inches on average, and that moisture usually being of a tropical nature. January is typically the driest month at an average 1.62 inches. I wouldn't rely on rain catchment for water here.....
That being said, directly on the coast the water table is fairly high, only 3 or 4 feet in places. Ranchers on Padre Island watered their cattle simply by digging pits a few feet down. This can be done in my back yard in Flour Bluff on the Encinal Peninsula as well (though it is against city "code"). Areas north and west of Corpus Christi Bay typically receive more rainfall, as do the Kingsville and Rio Grande Valley areas.
Land right on the coast is typically sandy loam, with large areas of clay as well. Crops grow well a few miles inland in the rich, brown soil. There is little tree cover from the north shore of Corpus Christi Bay and the Nueces River southward, mostly huisatch and mesquite. North of the bay, live oaks proliferate.
South of the Encinal Peninsula, the King, Kennedy, Yturria, and El Sauz ranches cover most of the land between the Laguna Madre and US 77, all the way to Port Mansfield, about 80 miles as the crow flies. The lone exceptions are Riviera Beach and Loyola Beach on the western end of Baffin Bay, near Kingsville. North and west of Kingsville is brush land, lots of smaller ranches, and little to no surface water.
On the plus side, fish are plentiful! Speckled trout, red drum, black drum, and southern flounder are the major varieties, along with sand trout, golden croaker, gafftop and hardhead catfish, the occasional snook, pompano, and offshore species like whiting, bluefish, king mackerel, spanish mackerel, wahoo, yellowfin and blackfin tuna, red/gray/vermilion/mutton/mangrove/and yellowtail snappers, amberjack, jewfish, strawberry/warsaw groupers, scamp, cobia...... We also have plentiful stone crab, blue crab, oysters, scallops on occasion, brown/white and Gulf species of shrimp, and more.
Migratory birds love this place as well. Many species of ducks and geese winter here, or at least stop by for a while (I hear mesquite grilled whooping crane is delicious! Heh heh heh....). There are many, many resident species of birds here. It's a bird shooter's paradise (both gun and camera).
And there are plenty of game critters here. Cotton tails galore, red squirrels, white tail deer out the wazoo, feral hogs, javelina, cows...... Oops, cows ain't game critters (and shootin' one of those is likely to get you shot back!) ha ha. Anyways, there you have it. South Texas Coastal Bend in a nutshell.....
How About Some Riddles...?
3 hours ago