Regarding the percentage of area to be irrigated, it has already been stated that one canal or distributary irrigates a far higher percentage than another. Generally when there is a high percentage in any tract, it is undesirable to cut it down unless it has very recently sprung up to the detriment of other tracts. In some remodelling projects a uniform percentage is taken on the whole area including both new and old irrigation. This plan is suitable when the percentage of old irrigation is not very high. In other cases the old irrigation to be provided for may be taken as the maximum area actually irrigated, a little being perhaps added for extensions. If the irrigation of considerable areas of jungle tracts is contemplated and if these consist of numerous small patches, a further percentage can be added for them. If there are large jungle tracts they can of course be dealt with separately and any suitable percentage adopted for them. The percentage for each portion of a remodelling project is not necessarily the same. If the discharge of a channel is increased, the waterways of bridges may need increasing. This can often be done (Chapter II., Art. 12) by making a floor at a low level. Or the waterway may be allowed to remain small, the floor being added at the bed level and the bridge then becoming an incomplete fall, (page 87). The fall in the water surface, though small, can be recognised and shown on the longitudinal section. In remodelling schemes, the longitudinal section should give all possible information. It should show not only the levels of bed and banks, but the F.S. levels (in blue figures) above and below all falls or regulators, and the levels of floors and waterways of bridges. The plan should show all watercourses and the “chaks” or areas assigned to them.[34] On each chak the actual average irrigation can be shown in blue figures and the proposed irrigation in red. The “draw-off” for each proposed outlet can then be shown on the longitudinal section. The area actually irrigated, as shown on the map, should in each case be the mean of at least three years, and if possible of five years. The number of years should be mentioned in a note on the map. Cross-sections of channels should always be drawn to natural scale, and not with the horizontal scale differing from the vertical. [34] The field maps mentioned on page 101 are prepared to a very large scale and show all watercourses. The maps should always be corrected up to date by the patwaris. The chak maps which are on a smaller scale--say 4 inches to the mile--can thus be kept correct. 7. =Remodelling of outlets.= When a channel is remodelled, the remodelling of the outlets may consist in alterations of the number or sites or in alterations of their sizes.