Abstract Urbanization is increasing worldwide, and it has drastic effects on groundwater systems with ramifications for water management. Effects can include overexploitation, subsidence, water quality deterioration, destruction of environmental resources, increased runoff, alteration of the permeability and porosity fields, and changes in recharge. Commonly, it is assumed that recharge decreases, but data indicate the opposite: Groundwater recharge increases because of leaky utility (water and sewage) systems and urban irrigation. Urban areas are hydrologically similar to karst settings because they possess internal drainage (storm sewers), surface streams (paved drainage ways) that flow after heavy rains, and a shallow permeability structure dominated by fractures, conduits, and caves (buried utility trenches, abandoned pipes, etc.) that evolves very quickly. Secondary porosity from underground construction is similar in magnitude to karst secondary porosity. These structures and utility trenches increase permeability and make prediction of groundwater flow and transport difficult. Recharge is grouped into the following categories: direct (from precipitation), indirect (from surface water bodies and leaky utility systems), localized (through preferential pathways such as sinkholes), and artificial. Indirect recharge is commonly ignored in urban water budgets, but water main losses range from 5% to over 60%. Additional recharge comes from leaky sewers, leakage from beneath homes and industries, and irrigation return flow (e.g., lawn overwatering). A case study of Austin, Texas, demonstrates significant indirect recharge and the difficulties in its estimation. Nearly 8% of Austin water main flow is lost to become recharge. However, lawn irrigation may be a larger source.

Eighty-one species of dinoflagellates and acritarchs have been identified from two sections of the Navarro Group in Texas. Forty-one species were distinguished from the Olmos and Escondido Formations from a 1170-foot core section in Frio County. Nearly all of those species and more than 30 additional taxa were identified from surface sections of the Neylandville Marl-Nacatoch Sand, Corsicana Marl, and Kemp Clay composited from several localities near Austin. The ranges of 56 of these entities are plotted to show zonation of the Navarro Group into three parts and tentative correlation of the Austin and Frio County sections. Twenty species found in the Neylandville-Nacatoch rocks near Austin were not found in the Frio County section, indicating that the base of the Navarro in Frio County is younger than the lower part of the Navarro in the Austin area, probably about early middle Corsicanan in age. An unconformity is demonstrated at the top of the Neylandville Marl-Nacatoch Sand in the Austin sections by the termination of range of these 20 species and by the first appearance of 15 additional species in the lowermost Corsicana beds. The ranges of nine forms terminate at approximately the position of the base of the Kemp Clay, to mark the base of the upper of the three acritarch-dinoflagellate zones. The termination of range, in this area, of Palaeohystrichophora infusorioides and the peak development of five other species at successively younger time-correlative levels in both sections furnish a basis for further subdivision of the Navarro and time-line correlations between the two sections about 135 miles apart. Pollen-spore/microplankton ratios in the Austin section indicate relative water depths or distance from shore, or both. Comparison of palynomorphs from other areas previously studied indicates that the Corsicana Marl and Kemp Clay, and comparable age strata of the Olmos and Escondido Formations, are probably about the same age as the Red Bank Formation of New Jersey and older than the Upper Moreno Formation of California.