The secondary source material for military operations along the Texas coastline isn't as well developed as other Civil War fronts but some older articles and newer books by Stephen Dupree and Stephen Townsend broadly cover the subject. A few battles, like Galveston and Sabine Pass (see Ed Cotham's wonderful books, are very well covered. Some areas require more digging.
A pair of not easy to find book length historical and archaeological reports published by Austin consulting firm Prewitt and Associates offer unique details about Confederate defensive preparations and Union blockading activities at sites located between Galveston and the upper end of Matagorda Bay. Sargent Beach Project (1994: Reports of Investigations, Number 98) by Martha Doty Freeman and Elton R. Prewitt discusses the history behind Confederate fortifications built to defend the mouth of Caney Creek, just beyond the north end of Matagorda Bay, as well as the findings of the archaeological investigation.
Also by Freeman and the Prewitt team is A History of Civil War Military Activities at Velasco & Quintana, Brazoria County, & Virginia Point, Galveston County, Texas (1995: Reports of Investigations, Number 103). In the book, Freeman discusses the economic importance of the rail connection between Houston and Galveston as well as the inland transportation and trade routes (especially the Galveston & Brazos Navigation Co. Canal) between Galveston Bay and the Brazos River, the inland passages increasing in profile with the tightening of the federal blockade of Galveston. Fortification efforts in this region, a large mid-coast span untouched by Union soldier boots but frequently exposed to naval bombardment, are meticulously described, focusing on the earthwork systems defending the mouth of the Brazos River and at Virginia Point (the spot where the Galveston, Houston & Henderson Railroad leaves the mainland and passes over West Bay to Galveston Island).
The history of the massive Confederate fort construction effort, which was effectively managed by gifted foreign-born engineers Julius Kellersberg and Valery Sulakowski with local slave gangs providing the labor, is presented at a level of detail found no where else. The Union navy frequently tested these defenses and their own vessel ordnance reports are reproduced in tabular format in the book. Research is heavily based on archival resources and government documents and the value of the historical text is greatly enhanced by an extensive collection of maps, tables, and drawings prepared by Prewitt staff. Many engineer drawings from the National Archives are also reproduced. The entire project was prepared under contract with the U.S. Corps of Engineers so an appendix also maps the historical sites to current locations, addressing ownership concerns. Anyone researching the Civil War on the Texas coast would do well to consult these fascinating Prewitt monographs (of which there are 3 in total*).
* - the two mentioned above plus an earlier study of Galveston Island's Fort San Jacinto, the last unseen by me. The Freeman pair that I have read are filled with information not available anywhere else at anything approaching comparable depth (including McKinney's revised Confederates on the Caney: An Illustrated Account of the Civil War on the Texas Gulf Coast from 1997).
[Special thank you to Sandy at Prewitt for sending me copies of the Freeman reports for my personal library, ending a years long quest]