Abstract Recent discoveries in offshore Tanzania and Mozambique highlight East Africa as an emerging world-class petroleum province. Estimates for this province total 12.5 BBO and 250 TCF of gas ( Brownfield et al. , 2012 ) as yet undiscovered hydrocarbons. Play-opening reservoir systems have been verified in Paleocene, Eocene, and at least two Oligocene deep water submarine fan and intra-slope channel complexes ( Law, 2011 ). Evidence continues to mount suggesting that the Late Cretaceous section may also contain deposits from similar depositional settings ( TPDC, 2003 ). There are indications that the petroleum system may contain oil as well as the established gas, and investigations are underway to determine if liquids are also present in the deep water areas. In short, the petroleum system components are all verified, what remains is the need to rapidly high grade what constitutes an enormous play area (> 0.5 million square kilometers) by establishing the extent and distribution of the deep-water reservoir systems. Therefore a strong impetus exists to develop techniques for high grading the area which can be performed on 2D regional (seismic-) data. One such technique is presented in this paper. It involves generating high-resolution horizon interpretations from the 2D seismic data. It enables not only the transforming of 2D seismic data into Wheeler (chronostratigraphic) domain ( Ligtenberg et al. , 2006 ; de Groot et al. , 2010 ; Qayyum et al. , 2012 ) but also helps in mapping depositional shifts and reservoir distribution.

Conversion of upland forest and prairie vegetation to agricultural land uses, following Euro-American settlement in the Upper Mississippi River System, led to accelerated runoff and soil erosion that subsequently transformed channels, floodplains, and wetlands on bottomlands. Halfway Creek Marsh, at the junction of Halfway Creek and the Mississippi River on Wisconsin’s western border, is representative of such historical transformation. This marsh became the focus of a 2005–2006 investigation by scientists from the U.S. Geological Survey, the University of Wisconsin–Madison, and the U.S. Environmental Protection Agency, who used an understanding of the historical transformation to help managers identify possible restoration alternatives for Halfway Creek Marsh. Field-scale topographic surveys and sediment cores provided data for reconstructing patterns and rates of historical overbank sedimentation in the marsh. Information culled from historical maps, aerial photographs, General Land Office Survey notes, and other historical documents helped establish the timing of anthropogenic disturbances and document changes in channel patterns. Major human disturbances, in addition to agricultural land uses, included railroad and road building, construction of artificial levees, drainage alterations, and repeated dam failures associated with large floods. A volume of approximately 1,400,000 m 3 , involving up to 2 m of sandy historical overbank deposition, is stored through the upper and lower marshes and along the adjacent margins of Halfway Creek and its principal tributary, Sand Lake Coulee. The estimated overbank sedimentation rate for the entire marsh is ~3,000 m 3 yr ‒1 for the recent period 1994–2006. In spite of reduced surface runoff and soil erosion in recent years, this recent sedimentation rate still exceeds by ~4 times the early settlement (1846–1885) rate of 700 m 3 yr ‒1 , when anthropogenic acceleration of upland surface runoff and soil erosion was beginning. The highest rate of historical bottomland sedimentation occurred from 1919 to 1936, when the estimated overbank sedimentation rate was 20,400 m 3 yr ‒1 . This rate exceeded by nearly 30 times the 1846–1886 rate. Artificial levees were constructed along the upper reach of Halfway Creek in the marsh during the early twentieth century to restrict flooding on the adjacent bottomlands. Anomalously high overbank sedimentation rates subsequently occurred on the floodplain between the levees, which also facilitated more efficient transport of sediment into the lower marsh bottomland. Although overbank sedimentation rates dropped after 1936, corresponding to the widespread adoption of soil-conservation and agricultural best-management practices, the continuation of anomalously high overbank sedimentation between the levees led to increased bank heights and development of a relatively deep channel. The deep cross-section morphology is commonly mistaken as evidence of channel incision; however, this morphology actually resulted from excessive overbank sedimentation. The historical metamorphosis of the Halfway Creek channel and riparian wetlands underscores the importance of understanding the long-term history of channel and floodplain evolution when restoration of channels and riparian wetlands are under consideration. Sedimentation patterns and channel morphology for Halfway Creek Marsh probably are representative of other anthropogenically altered riparian wetlands in the Upper Mississippi River System and similar landscapes elsewhere.

Hydraulic gold-mining tailings produced in the late nineteenth century in the Sierra Nevada foothills of California caused severe channel aggradation in the lower Feather and Yuba Rivers. Topographic and planimetric data from historical accounts, maps, topographic surveys, vertical sections, aerial photographs, and LiDAR (light detection and ranging) data reveal contrasting styles of channel change and floodplain evolution between these two rivers. For example, levee cross-channel spacings up to 4 km along the lower Yuba River contrast with spacings <2 km on the larger Feather River. More than a quarter billion cubic meters of hydraulic-mining sediment were stored along the lower Yuba River, and the wide levee spacing was intentionally maintained during design of the flood-control system to minimize delivery of sediment to navigable waters downstream. Consequently, the lower Yuba floodplain has a multithread high-water channel system with braiding indices >12 in some reaches. Some of the larger of these channels remain clearly visible on aerial photographs and LiDAR imagery in spite of intensive agricultural leveling. Narrow levee spacings on the Feather River were designed to encourage transport of mining sediment downstream and keep the channel clear for navigation. Levee spacings on the lower Feather River reached a minimum near the turn of the twentieth century, when floodplain widths were reduced at several constricted reaches to <250 m. Historical data indicate that the general channel location of the lower Yuba River had stabilized by the end of the nineteenth century, whereas substantial channel avulsions began later and continued into the twentieth century on the lower Feather River. The striking contrasts in channel change between the Yuba and Feather Rivers are due, at least in part, to different river-management strategies, although the Yuba River received much more sediment. Early river engineering of these channels represented the first efforts at integrated river-basin management west of the Mississippi, so the observed long-term effects are instructive. Modern river management should consider how the disturbance factors in these channels and the imprint of early river management affect the modern morphologic stability and sediment-production potential of the channel and floodplain.