Scarps and wadis feature long vertical cliffs with angular (usually 30 degrees) pediments at their base, and rise out of the lower erosion surface below, often called the peneplain. The wadis emerge out of the scarp cliffs, face at right angles and branch at near right angles further up inside the wadis. Water is often trapped in scour holes at the top of scarp cliffs. Water can also be stored in deep sands and silts especially if gabion dams are built inside wadis where increased shade extends storage time. These complex landscapes have traditionally been well designed for comfortable productive human settlements. Kopje, mesas and buttes are all features of this landscape.
Residuals, domes and inselbergs are simple systems of large individual rocks like Uluru (Ayres Rock) in Australia and large solid rock ranges. These all have guaranteed rainwater runoff which when it is captured can be carefully directed to production systems. Rarely do these have caves or pronounced valleys of any depth.
Fold Mountains are the most extensive features of deserts and combine features of both inselbergs and scarps, and are generally more complex. The folds are either synclines down-flexed or anticlines up-flexed, which commonly erode to form long river valleys. Many opportunities exist for designing dams and large dams are possible with extreme caution, the preference being many small dams accumulating the same volume of water and more. Swales and controlled contour flows of water off high valley stream lines to small dams can become the start of a totally designed and patterned landscape.
Dune country occurs over pavements or as dune fields all shaped by wind. The smallest shapes being ripples, traverse dunes and regular ridges, oblique dunes, longitudinal dunes aligned with the wind, bachans, crescents pointing down wind, sand seas with of wave-like forms. Ergs are giant sand ridge lines, draas are the largest form as a stationary small mountain of sand. Pitting, seed pellets, planting baskets, mulch mats, woven fences and even the spraying of tar oils can be used to stabilize and re-vegetate typical sand dune country.
Depressions and basins are low flat areas or nearly circular depressions on a large scale are called tectonic basins and on the next scale down deflection hollows.
Scalds are the name given to clay pans where water flows in and fills the area seals and the water flows out the lower side. Very low soft earth banks graded up on the lower side will hold back large amounts of floodwater, which when soaked in will be enough to plant up and recover the area.
Claypans fill in rains and rarely over-flow allowing seasonal swamp type vegetation and animal habitat. Earth banks to hold back more water, ripping, pitting, seeding the claypan floor in the dry season will allow a diverse productive system to be developed. The establishment of herbs and needle-leaf mulch species will enhance establishment.
Saltpans and salt lakes hold meters of water in floods and when the water evaporates huge quantities of salt are left behind. Only on the margins will salt tolerant plants grow.
Gilgais are small hollows 3-5 meters across formed by patches of clay, which swell and shrink in depth with rain. The hollows can be linked up and the whole area becomes very diverse in plant species. If these are over grazed they become sand filled. The clay washes away and small sand mounds appear. The area becomes unstable and loses most of its vegetation.
Flood-outs, gullies and badlands are also called flat-outs or run-outs, ever widening close to flat floors of valleys as they leave hills. These streams are very shallow, wide and stable and water absorbs over a wide area of plains. The overgrazing of these leads to occurrence of severe steep side gully erosion.
Diversion of water flow from the head of the erosion gullies to diversion channels and out over long level sill spillways with pioneer tree planting. It is crucial to stop over grazing and prevent further cutting back of the gullies. Slopes on either side of erosion gullies can be ripped at 1000-1 slope down hill away to the ridge lines. Inside the gullies frequent series of low silt trap gabions can be constructed to grow pioneer trees and later fruit trees.
Stone gibber deserts cover large areas where the stones were once part of the soil structure but constant wind erosion has blown away the soil leaving the stones exposed. Stone swale banks loose piled on contour every 10-20 meters soak in large amounts of run-off making it possible to plant pioneer tree lines. The tree lines greatly reduce wind erosion and combing the air for small soil and organic particles. Swale trenches can be excavated just up hill from each stone swale bank to increase the effect of water infiltration increasing tree growth.
Once trees are established the inter-swale area can planted to crops.
Lower foothills and plains: even land that looks completely flat to the human eye has some slope and water can be harvested with very shallow swales. Swale banks just half a meter high can back up water for a huge distance. Mulch species can be seeded once water soaks into our pelleted seed spread to wait for rain. So much water can be harvested that some water can be released with controlled slide gates to soak a smaller walled field to grow a crop. If remnant species of trees remain, semi circular swales can be sited around the lower side of these, which will capture the tree seed, organic material, manures and soak in rainwater run off, these can be connected in groups or series to totally prevent run-off. Most of these low swale banks quickly establish volunteer local tree and shrub species.